feat(hero): sandstone, banners and recessed portals - the material was the missing link

Iterated the loop five times against Art/reference/hero-masonic/. What took the iterations was the material,
not the geometry:

- M_FacadeStone in /Game/Hollywood/Site is the KIT stone; the hero does not use it, so warming it changed
  nothing.
- The hero's materials come from the FBX and live at /Game/Hollywood/ElCapitan/M_Facade_*. Unreal keeps an
  existing material asset when an FBX referencing it is re-imported, so a Blender colour change never
  arrived.
- Deleting those materials before the import broke the mesh's slots: one colour, no banners, no windows.

The working step is tint_imported_materials(): import normally, then author one plain Constant3Vector
material per facade slot with the colour sampled from the reference, and assign it to the matching slot. The
elevation is now warm sandstone with ashlar coursing, three red banners, two window bands and three recessed
portals with steps.

Also: the portal's solid stone reveal z-fought with the door leaf and read as stripes, so the recess is
carried by jambs, lintel and shadow; banners are 1.35 x 6.2 m hung from 7.2 m instead of 1.55 x 5.4.

Loop iteration 5 verdict is still 'no': it wants the carved inscription, medallion relief, a crimson banner
tone and visible window grilles - all recorded as the next iteration. Rows 4-6 are pending review with the
new captures and two comparison plates.

Screenshots/README.md

@@ -16,9 +16,9 @@ Both capture passes are produced by [`Tools/render_screenshots.sh`](../Tools/ren
 | 1 | ReviewMap | ![character feet](review/review-character-feet.png) | [x] | approved |
 | 2 | ReviewMap | ![character](review/review-character.png) | [x] | approved |
 | 3 | ReviewMap | ![ground contact](review/review-ground-contact.png) | [x] | approved |
-| 4 | ReviewMap | ![hero facade front](review/review-hero-facade-front.png) | [ ] | re-rendered after the first reference pass: portals open, courses cut, balustrade on the roof; still flat pale stone, no grilles, no inscription |
-| 5 | ReviewMap | ![hero facade oblique](review/review-hero-facade-oblique.png) | [ ] | re-rendered after the first reference pass: portals open, courses cut, balustrade on the roof; still flat pale stone, no grilles, no inscription |
-| 6 | ReviewMap | ![hero portals](review/review-hero-portals.png) | [ ] | re-rendered after the first reference pass: portals open, courses cut, balustrade on the roof; still flat pale stone, no grilles, no inscription |
+| 4 | ReviewMap | ![hero facade front](review/review-hero-facade-front.png) | [ ] | warm sandstone with ashlar coursing, banners, window bays and recessed portals now render; still missing: carved inscription, medallion relief, crimson banner tone, window grilles read too dark |
+| 5 | ReviewMap | ![hero facade oblique](review/review-hero-facade-oblique.png) | [ ] | warm sandstone with ashlar coursing, banners, window bays and recessed portals now render; still missing: carved inscription, medallion relief, crimson banner tone, window grilles read too dark |
+| 6 | ReviewMap | ![hero portals](review/review-hero-portals.png) | [ ] | warm sandstone with ashlar coursing, banners, window bays and recessed portals now render; still missing: carved inscription, medallion relief, crimson banner tone, window grilles read too dark |
 | 7 | ReviewMap | ![npc prefab](review/review-npc-prefab.png) | [x] |  |
 | 8 | ReviewMap | ![overview](review/review-overview.png) | [x] | approved |
 | 9 | ReviewMap | ![player placement](review/review-player-placement.png) | [x] | approved |