feat(geo): adopt Mapbox building calibration (3.1 m per level)

Owner decision: adopt the two findings from the Mapbox cross-check.

- LEVEL_HEIGHT 3.2 -> 3.1 m in block_height_report.py and the Blosm
  --level-height default; every levels-derived building drops ~0.6 m per 6
  levels, matching Mapbox.
- HEIGHT_OVERRIDES for the three rear building=yes/apartments structures that
  Mapbox gives as single storey (3.0 m) where our 2-level fallback rendered
  6.4 m blocks.
- classify_height() takes an optional way_id so overrides apply; the Mapbox
  cross-check passes it and now reports 66 match / 6 non-building / 0 disagree.
- Geometry follows: blockout regenerated at 3.1 (frontage object names
  preserved, 6/6 exported), frontage re-imported, DemoMap rebuilt, packaged
  -qaselftest PASS (walk, reset, pause, transect 0 holes, wall probe 0/35).
- Docs: Art/blender/README scale table + a note that Blosm adds ~1.9 m roof mass
  above levels x levelHeight; TODO item closed; MEMORY records the gotcha that
  blockout regeneration must re-verify the element.* frontage mapping.

TODO.md

@@ -15,7 +15,7 @@ Suggested blender skills: **references** (reference-image-match and visual-match
 
 ### Patch tasks - active - 01a1b26b-3c94-707f-9665-2f6b4a79b564 (branch `scale-facade-0.1.2`)
 
-- [ ] Correct building scale and street proportions flagged against references. **Cross-check available:** `Geo/tools/mapbox_buildings.py` merges our OSM heights with Mapbox's building data for the same footprints (72 buildings: 58 match, 5 close, 3 disagree, 6 non-building). Three rear `building=yes`/`apartments` structures still render at our 2-level guess (6.4 m) against Mapbox's 3.0 m; and every `levels × 3.2 m` building is 0.6 m taller per 6 levels than Mapbox implies, i.e. **Mapbox suggests 3.1 m per level**. Neither is applied yet — decide from the reference photography.
+- [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.
 - [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.
 - [ ] 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. **Measured 2026-11-08 from the built mesh** (`Art/blender/hero/hero-facade-2026-11-07.blend`): envelope 0–14.50 m; stylobate 0–2.00; columns 2.00–7.95; capitals 7.95–8.90; entablature 8.90–12.30; parapet 12.30–14.50. So the colonnade (columns + capitals) is **6.90 m = 47.6 %** of the height — inside the range only at the low end. Bringing it to ~55 % needs ~+1.0 m of colonnade taken from the attic/parapet zone, which also carries the motto band and medallions, so it is a **design decision that needs the reference photographs side by side** — left open for owner visual review rather than guessed.