feat(web): tint objects by their ColorDiffuse

Model ColorDiffuse in shared types and multiply each viewer's material color by the per-object tint, including textured faces and loaded custom models.

docs/full-setup-view.md

@@ -110,7 +110,9 @@ view and the full-setup view.
   caches
 - `apps/web/src/components/viewers/transform.ts` — new TTS→three.js placement
   conversion
-- `packages/shared/src/types.ts` — add `TTSObjectTransform`
+- `apps/web/src/components/viewers/sharedResources.ts` — `objectTint`/
+  `tintedColor` helpers for the per-object `ColorDiffuse` tint
+- `packages/shared/src/types.ts` — add `TTSObjectTransform` and `ColorDiffuse`
 - `apps/web/src/pages/FullSetupPage.tsx` — new
 - `apps/web/src/App.tsx` — route
 - `apps/web/src/pages/ModPage.tsx` — nav link