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_build_review_map.py

@@ -300,6 +300,12 @@ try:
             # on the north sidewalk looking along the crosswalk itself, which is
             # the pedestrian's view and shows the zebra bars as bars.
             ("demo-crossing", unreal.Vector(-15250, -2500, 400), unreal.Vector(-14956, 400, 150)),
+            # 0.1.6 retail frontage: 6800 Lee Drug (X -3340..-1417, face Y +1467)
+            # and 6806-6820 (X -6618..-3297, face Y +1252). Stand on the north
+            # sidewalk at 2 m, look south with a level horizon so the parapets and
+            # the cornice line read as horizontals. 68 deg covers both frontages at
+            # this distance; the ends crop rather than the elevation leaning.
+            ("demo-retail-frontage", unreal.Vector(-4700, -2000, 200), unreal.Vector(-4700, 1400, 560), 68.0),
             # the two north-side background buildings (TCL, Tussaud's) seen from
             # the south across Hollywood Blvd. Probed world-space (2026-11-08):
             # TCL bbox X -22889..-18442, Y -9431..-1802; Tussaud's X -27071..