feat: 2.5D stage 6 — public setting, raised tiles, soft sun, theme-free walls (#649)

- settings.volumetric_view (General settings › Display, third switch) replaces
  the alpha entry, the header projection toggle and the phone-menu item; one
  rule for card, sidebar page and kiosk; editors stay Flat; backend accepts
  only a boolean, support package copies it.
- Raised tiles in 2.5D View: no ring, rounded body min(0.275 D, 0.3 h), edge
  0.1 D with the lab filters, ×1.12 size also in layout/collision, lift
  0.075 D, one floor-shadow layer under all markers (theme × floor table),
  frames hugging tile and edge (Alert > Focus > Selected > Hover), forced
  colours without edge and shadow (src/iso-tiles.ts, styles/iso-tiles).
- Soft sun wash instead of projected Flat wedges (src/iso-sun.ts): same gates
  and windows as sun_rays, length from elevation, parallelogram along the sun,
  tone and streaks by floor lightness, sill line.
- Walls take the user's wall colour (top opaque, sides × .77/.68/.60); theme
  rules for walls/openings/labels removed; furniture uses the Flat stroke rule.
- Smokes smoke_iso_tiles/iso_sun/iso_theme_walls/volumetric_setting, 16 new
  mutants, acceptance scenes STAGE6_ACCEPTANCE_SCENARIOS (golden with their
  Linux CI baselines), ACCEPTANCE.md side by side.

Issue: #649
User-Visible: yes

tsconfig.test.json

@@ -21,7 +21,7 @@
     "src/resize.ts", "src/resize-labels.ts", "src/resize-controller.ts", "src/wall-record-preservation.ts",
     "src/rules.ts",
     "src/devices.ts", "src/device-inbox.ts",
-    "src/virtual-light-state.ts", "src/config-store.ts", "src/config-reload-authority.ts", "src/config-write-conflict.ts", "src/summary-panel.ts", "src/summary-panel-metrics.ts", "src/summary-panel-i18n.ts", "src/summary-panel-identity.ts", "src/summary-panel-picker.ts", "src/summary-panel-runtime-loaded.ts", "src/header-menu.ts",
+    "src/virtual-light-state.ts", "src/config-store.ts", "src/config-reload-authority.ts", "src/config-write-conflict.ts", "src/summary-panel.ts", "src/summary-panel-metrics.ts", "src/summary-panel-i18n.ts", "src/summary-panel-identity.ts", "src/summary-panel-picker.ts", "src/summary-panel-runtime-loaded.ts", "src/header-menu.ts", "src/iso-materials.ts", "src/iso-tiles.ts", "src/iso-sun.ts",
     "src/backdrop-probe.ts",
     "src/types.ts", "src/editors/dialog-baseline.ts", "src/editors/color-tile-ink.ts", "src/editors/general-form-state.ts", "src/editors/space-form-state.ts", "src/editors/marker-form-state.ts", "src/editors/room-form-state.ts",
     "src/space-geometry.ts", "src/junction-limits.ts", "src/room-gear-drag.ts",