feat(hero): Ionic base and abacus, medallions onto the parapet face

Detail pass on the hero, all verified by measuring the built mesh:

- Column base moulding: a 1.36 m wide, 0.22 m tall cylinder at each shaft foot
  (2.00-2.22 m). The shaft previously started straight off the square pedestal,
  so the base never read in silhouette.
- Abacus: a 1.30 m square, 0.14 m thick slab over each capital. It takes the top
  of the capital zone, so the colonnade still ends at 9.70 m and the 53.1 %
  proportion is unchanged.
- Medallions fixed: they were built with the Z-axis cylinder helper, so the two
  'discs' were pancakes lying flat on the parapet coping (1.1 x 1.1 x 0.02,
  z 14.02-14.04). New disc_on_wall() helper rotates the cylinder 90 deg about X;
  they now stand 1.1 m across on the parapet face (y -1.32..-1.28,
  z 13.05..14.15).

Hero rebuilt (95 parts, 2420 tris, still 14.50 m), re-imported, DemoMap rebuilt,
screenshot set re-rendered. Part report records the new dims and their assumption
notes. Screenshots README notes the detail pass.

Art/blender/hero/hero-facade-2026-11-07.json

@@ -3,18 +3,18 @@
   "frame": "project frame, metres, X east Y north Z up",
   "bounds_m": {
     "min": [
-      -13.02,
+      -13.08,
       -12.5,
       0.0
     ],
     "max": [
-      13.02,
-      0.07,
+      13.08,
+      0.13,
       14.5
     ],
     "size": [
-      26.04,
-      12.57,
+      26.16,
+      12.63,
       14.5
     ]
   },
@@ -37,6 +37,24 @@
       ],
       "evidence": "6 columns at 4.96 m centres (sibling notes x measured frontage)"
     },
+    {
+      "object": "Hero_ColumnBase_x6",
+      "dims_m": [
+        1.36,
+        1.36,
+        0.22
+      ],
+      "evidence": "assumption: Ionic base moulding; photographs show a wider base at the shaft foot"
+    },
+    {
+      "object": "Hero_Abacus_x6",
+      "dims_m": [
+        1.3,
+        1.3,
+        0.14
+      ],
+      "evidence": "assumption: square abacus under the architrave, as Ionic capitals carry"
+    },
     {
       "object": "Hero_Architrave",
       "dims_m": [
@@ -86,10 +104,10 @@
       "object": "Hero_Medallion_x2",
       "dims_m": [
         1.1,
-        1.1,
-        0.02
+        0.04,
+        1.1
       ],
-      "evidence": "photographs: two stone discs beside the motto"
+      "evidence": "photographs: two stone discs beside the motto, mounted on the parapet face"
     },
     {
       "object": "Hero_Stylobate",

TODO.md

@@ -16,7 +16,7 @@ Suggested blender skills: **references** (reference-image-match and visual-match
 ### Patch tasks - active - 01a1b26b-3c94-707f-9665-2f6b4a79b564 (branch `scale-facade-0.1.2`)
 
 - [x] Correct building scale and street proportions flagged against references. **Mapbox adopted 2026-11-09.** `Geo/tools/mapbox_buildings.py` merges our OSM heights with Mapbox's building data for the same footprints; after adopting its two findings the cross-check reports **66 match, 6 non-building, 0 disagreements**. Adopted: **`LEVEL_HEIGHT` 3.2 → 3.1 m** (`block_height_report.py`, and the Blosm `--level-height` default), plus explicit `HEIGHT_OVERRIDES` (3.0 m) for the three rear `building=yes`/`apartments` structures Mapbox gives as single-storey. Blockout regenerated, frontage re-exported/re-imported, DemoMap rebuilt; packaged `-qaselftest` all PASS. Measured effect: 6922 42.1 → 39.1 m, El Capitan Theatre 20.0 → 20.5 m (both now ~1.9 m above their table height = roof mass).
-- [ ] Refine hero façade details where reference photography shows discrepancies. **Started 2026-11-09:** built `Tools/facade_detail_concepts.py`, which generates architectural detail plates from the local reference photographs with an image model (`--list` free, `--all` generates, sidecars + `-vN` no-overwrite, output gitignored). Six **frontal building** studies generated locally under `Art/reference/facade-details/` (whole elevation, entrance in its facade, building with neighbours, pavement view, three-quarter, theatre frontage) — rephrased on owner instruction to show the building/entrance/neighbours rather than close-up detail crops. **First fix from the measurement pass:** window panes were 1.44 m in front of the wall (ahead of the columns) and now sit on the wall plane behind the colonnade. Remaining: use the plates to correct the capital/base profiles and the medallion/cornice detail.
+- [ ] Refine hero façade details where reference photography shows discrepancies. **Started 2026-11-09:** built `Tools/facade_detail_concepts.py`, which generates architectural detail plates from the local reference photographs with an image model (`--list` free, `--all` generates, sidecars + `-vN` no-overwrite, output gitignored). Six **frontal building** studies generated locally under `Art/reference/facade-details/` (whole elevation, entrance in its facade, building with neighbours, pavement view, three-quarter, theatre frontage) — rephrased on owner instruction to show the building/entrance/neighbours rather than close-up detail crops. **First fix from the measurement pass:** window panes were 1.44 m in front of the wall (ahead of the columns) and now sit on the wall plane behind the colonnade. **Detail pass 2026-11-09 (all measured on the built mesh):** added an Ionic base moulding (1.36 m × 0.22 m) at each shaft foot and a square abacus (1.30 m × 0.14 m) over each capital, taking the abacus out of the capital zone so the colonnade still ends at 9.70 m; re-oriented the two parapet medallions, which were flat discs lying on the coping (1.1 × 1.1 × 0.02 in the wrong axes) instead of discs on the parapet face; window panes moved onto the wall plane. Hero is now 2 420 tris across 95 parts, still 14.50 m. Cornice/dentil profile refinement remains.
 - [x] **Replace the placeholder heights.** **Resolved 2026-11-08 — they were never unknown buildings.** The three "guessed" ways are not building volumes at all: `1360755125` and `1360755126` are `building=roof` at `layer=1` (elevated canopies) and `1417995292` is `amenity=shelter` / `shelter_type=public_transport` (a transit shelter). The report defaulted them to "2 levels × 3.2 m" and produced the bogus 6.4 m. `Geo/tools/block_height_report.py` now classifies roof/shelter explicitly and reports **0 guessed heights**: all 15 block volumes have a real `height` tag, a `building:levels` derivation, or are correctly excluded as non-building volumes. No photograph measurement was needed, and no frontage building was affected.
 - [x] Resolve the remaining unknown on the hero: the colonnade currently occupies about 45 % of the height against roughly 50–60 % in the photographs. Fix the vertical proportions. **Fixed 2026-11-09.** Measured baseline: colonnade (columns + capitals) 6.90 m of the 14.50 m envelope = **47.6 %**, because the entablature (3.40 m) and parapet (2.20 m) left only 7.90 m for the order. Thinned both to **3.00 m** and **1.80 m** (`Tools/hero_facade_build.py`), which lifts the colonnade to **7.70 m = 53.1 %** — inside the photographed 50–60 % band, with the 14.50 m envelope, the motto band and the medallions unchanged in position relative to the parapet. Hero rebuilt, re-imported (bounds 2604 × 1257 × 1450 cm) and re-rendered.
 - [ ] Tag `v0.1.2` and write `CHANGELOG.md` entry; then remove this section.

Tools/hero_facade_build.py

@@ -88,6 +88,25 @@ def cylinder(name, x, y, z0, z1, radius, material, vertices=24):
     return obj
 
 
+def disc_on_wall(name, x, y, z, radius, thickness, material=None, vertices=24):
+    """A round disc mounted vertically on a wall face.
+
+    `cylinder()` builds along Z, so a "medallion" made with it is a pancake lying
+    flat on top of the parapet rather than a disc on its face — which is what the
+    first build did (1.1 m across in Y, 0.02 m thick in Z, sitting at the coping).
+    This rotates the cylinder 90 degrees about X so the axis points along Y and
+    the disc faces the street.
+    """
+    obj = cylinder(name, x, y, z - thickness / 2.0, z + thickness / 2.0,
+                   radius, material, vertices=vertices)
+    obj.rotation_euler = (math.radians(90.0), 0.0, 0.0)
+    bpy.ops.object.select_all(action="DESELECT")
+    obj.select_set(True)
+    bpy.context.view_layer.objects.active = obj
+    bpy.ops.object.transform_apply(location=False, rotation=True, scale=True)
+    return obj
+
+
 def make_material(name, rgba, roughness=0.75):
     mat = bpy.data.materials.new(name)
     mat.use_nodes = True
@@ -136,14 +155,32 @@ def build():
         col_xs.append(x)
         cube(f"Hero_Pedestal_{i + 1}", x, -0.62, PEDESTAL_H + 0.27,
              1.24, 1.24, 0.54, stone)
-        cylinder(f"Hero_Column_{i + 1}", x, -0.55, PEDESTAL_H + 0.55,
-                 PEDESTAL_H + 0.55 + (HEIGHT - ENTABLATURE_H - PARAPET_H - PEDESTAL_H - 0.55 - CAPITAL_H),
+        # Base moulding: a taller, wider cylinder where the shaft meets the
+        # pedestal. Without it the shaft starts straight off a square plinth,
+        # which is not how an Ionic base reads in silhouette.
+        base_z0 = PEDESTAL_H + 0.55
+        base_h = 0.22
+        cylinder(f"Hero_ColumnBase_{i + 1}", x, -0.55, base_z0, base_z0 + base_h,
+                 0.68, stone, vertices=20)
+        shaft_z0 = base_z0 + base_h
+        cap_z0 = HEIGHT - ENTABLATURE_H - PARAPET_H - CAPITAL_H
+        cylinder(f"Hero_Column_{i + 1}", x, -0.55, shaft_z0, cap_z0,
                  COLUMN_D / 2.0, stone)
-        cylinder(f"Hero_Capital_{i + 1}", x, -0.55,
-                 HEIGHT - ENTABLATURE_H - PARAPET_H - CAPITAL_H,
-                 HEIGHT - ENTABLATURE_H - PARAPET_H, 0.62, stone, vertices=16)
+        # Capital block, then the square abacus that carries the architrave.
+        # The abacus takes the top 0.14 m of the capital zone so the colonnade
+        # still ends at HEIGHT - ENTABLATURE_H - PARAPET_H (proportion unchanged).
+        abacus_h = 0.14
+        cylinder(f"Hero_Capital_{i + 1}", x, -0.55, cap_z0,
+                 HEIGHT - ENTABLATURE_H - PARAPET_H - abacus_h, 0.62, stone, vertices=16)
+        cube(f"Hero_Abacus_{i + 1}", x, -0.55,
+             HEIGHT - ENTABLATURE_H - PARAPET_H - abacus_h / 2.0,
+             1.30, 1.30, abacus_h, stone)
     note("Hero_Column_x6", (COLUMN_D, COLUMN_D, HEIGHT - ENTABLATURE_H - PARAPET_H - PEDESTAL_H),
          f"6 columns at {COLUMN_BAY} m centres (sibling notes x measured frontage)")
+    note("Hero_ColumnBase_x6", (1.36, 1.36, 0.22),
+         "assumption: Ionic base moulding; photographs show a wider base at the shaft foot")
+    note("Hero_Abacus_x6", (1.30, 1.30, 0.14),
+         "assumption: square abacus under the architrave, as Ionic capitals carry")
 
     # --- entablature and parapet ------------------------------------------
     ent_z0 = HEIGHT - ENTABLATURE_H - PARAPET_H
@@ -167,11 +204,13 @@ def build():
          FRONTAGE_W - 3.0, 0.08, 0.85, stone_dark)
     note("Hero_MottoBand", (FRONTAGE_W - 3.0, 0.08, 0.85), "photographs: motto panel above the colonnade")
 
-    # Medallions either side of the inscription.
+    # Medallions either side of the inscription: discs on the parapet face, not
+    # pancakes on the coping (see disc_on_wall).
     for i, x in enumerate((-6.2, 6.2), start=1):
-        cylinder(f"Hero_Medallion_{i}", x, -1.36, HEIGHT - PARAPET_H / 2.0 + 0.42,
-                 HEIGHT - PARAPET_H / 2.0 + 0.44, 0.55, stone_dark, vertices=20)
-    note("Hero_Medallion_x2", (1.1, 1.1, 0.02), "photographs: two stone discs beside the motto")
+        disc_on_wall(f"Hero_Medallion_{i}", x, -1.30, HEIGHT - PARAPET_H / 2.0,
+                     0.55, 0.04, stone_dark, vertices=20)
+    note("Hero_Medallion_x2", (1.1, 0.04, 1.1),
+         "photographs: two stone discs beside the motto, mounted on the parapet face")
 
     # --- entrances ---------------------------------------------------------
     # Three portals between column pairs, each with its own short flight. The