feat(facades): 0.1.6 retail frontage first pass — Lee Drug and 6806-6820

Models the two retail buildings beside the hero from their own photograph rather
than the generic kit: bronze cornice, mural row, lettering band, stepped Deco
parapet and rounded corner tower on 6800 Lee Drug; burgundy fascia, pilasters,
white-framed windows and banded parapet on 6806-6820. Reference analysis written
before any geometry (Art/blender/retail/ref-analysis.md), every unmeasured
proportion carried into the part report as an assumption.

6822 Budget is deferred, not guessed: no photograph of it exists and the 6.0 x 5.5 m
sliver cannot be read out of the neighbour shot.

Pipeline fixes found on the way:
- render_screenshots.sh called ./Engine/... for the capture step while every
  commandlet used the absolute path; set -e killed the script at 127 *after* the
  maps were rebuilt, so screenshots silently stayed a day old.
- the facade kit applies to every Frontage_*/North_* actor, so it pasted its own
  language over the new modelled facades; it now skips them, and the trim stages as
  RetailTrim_*.
- pure bay arithmetic moved to Tools/_common.py so it is unit-testable without
  Blender (4 new tests, 82 total pass).

Known gaps recorded in Screenshots/README.md, not hidden: the parapet reads as a
blank band, murals and lettering do not resolve at review distance, the tower is a
plain cylinder, and the review camera crops the east end.

Tools/ue_import_retail_detail.py

@@ -0,0 +1,94 @@
+# Import the retail frontage trim (6800 Lee Drug, 6806–6820) into Unreal.
+#
+#   blender -b --factory-startup --python Tools/retail_frontage_build.py -- \
+#       --out /tmp/gigline/retail --report /tmp/gigline/retail-report.json
+#   <engine>/Engine/Binaries/Linux/UnrealEditor-Cmd <uproject> -run=pythonscript \
+#     -script=<repo>/Tools/ue_import_retail_detail.py -nullrhi -unattended -nopause -stdout
+#
+# Two meshes arrive, one per building, each already at its world position in the
+# project frame (the FBX carries the offset), so staging spawns at the origin.
+# Destination: /Game/Hollywood/Frontage/<name> — same folder as the block frontage
+# so the demo builder stages them together.
+#
+# Result file: /tmp/gigline/retail-import.txt
+
+import glob
+import os
+
+import unreal
+
+SRC = "/tmp/gigline/retail"
+DEST = "/Game/Hollywood/Frontage"
+RESULT = "/tmp/gigline/retail-import.txt"
+lines = []
+
+
+def log(msg):
+    lines.append(str(msg))
+    unreal.log(str(msg))
+
+
+def import_fbx(path, name):
+    task = unreal.AssetImportTask()
+    task.filename = path
+    task.destination_path = DEST
+    task.destination_name = name
+    task.automated = True
+    task.save = True
+    task.replace_existing = True
+
+    ui = unreal.FbxImportUI()
+    ui.import_mesh = True
+    ui.import_materials = True
+    ui.import_textures = False
+    ui.import_as_skeletal = False
+    smd = ui.static_mesh_import_data
+    smd.import_uniform_scale = 1.0
+    smd.combine_meshes = True
+    smd.convert_scene_unit = False
+    smd.force_front_x_axis = False
+    smd.normal_import_method = unreal.FBXNormalImportMethod.FBXNIM_IMPORT_NORMALS
+    task.options = ui
+    unreal.AssetToolsHelpers.get_asset_tools().import_asset_tasks([task])
+
+    mesh = unreal.EditorAssetLibrary.load_asset(f"{DEST}/{name}")
+    if mesh is None:
+        log(f"MISSING after import: {DEST}/{name}")
+        return None
+
+    # Trim is decoration on a solid the player already collides with: no collision
+    # of its own, otherwise the cornice and mullions become snag points.
+    try:
+        body = mesh.get_editor_property("body_setup")
+        body.set_editor_property("collision_trace_flag",
+                                 unreal.CollisionTraceFlag.CTF_USE_COMPLEX_AS_SIMPLE)
+        mesh.set_editor_property("body_setup", body)
+    except Exception as exc:  # noqa: BLE001
+        log(f"{name}: collision flag not set ({exc!r})")
+
+    box = mesh.get_bounding_box()
+    mn, mx = box.min, box.max
+    log(f"{name:22} X {mn.x:8.0f}..{mx.x:8.0f}  Y {mn.y:7.0f}..{mx.y:7.0f}  "
+        f"Z {mn.z:5.0f}..{mx.z:5.0f}  slots {len(mesh.get_editor_property('static_materials'))}")
+    return mesh
+
+
+def main():
+    files = sorted(glob.glob(os.path.join(SRC, "*.fbx")))
+    if not files:
+        log(f"no FBX in {SRC}; run Tools/retail_frontage_build.py first")
+        return
+    for path in files:
+        import_fbx(path, os.path.splitext(os.path.basename(path))[0])
+    unreal.EditorLoadingAndSavingUtils.save_dirty_packages(True, True)
+
+
+try:
+    main()
+except Exception as exc:  # noqa: BLE001
+    import traceback
+    log(f"FAILED: {type(exc).__name__}: {exc}")
+    log(traceback.format_exc())
+
+with open(RESULT, "w") as f:
+    f.write("\n".join(lines) + "\n")