Epic 5 Phase 1 — form is a mesh, actors have parity with SDF

meshes.js now mirrors shader-contract.js verbatim:
- jsCastSDF rotates by -tilt (matching GLSL column-major mat2), hollow
  excluded during outer-radius search so annular SDFs sample correctly,
  radial search probes without hollow then punches hole separately.
- castShape samples 64 segments, inner hole scaled by hollow width.
- formToGeometry uses formDepth (u_formDepth = r.z*depth half-extent),
  capsule h correctly half-height, sphere as scaled unit sphere, prism
  extruded with proper halfDepth and centered; bevel thickness from
  part.round.
- actorToGeometry preserves per-part op/blend userData, uses YXZ Euler
  for yaw/pitch (matches formRot), mirrors radial/mirror/stack symmetry
  exactly as shader formFold does.

Shared camera wired live: Show.renderFrame drives
Compositor.updateSharedCamera from ArcDriver framing/personality/time
and injects sharedCamera into each active ModelLayer — pure f(frame,look)
so seek === playback. ArcDriver exposes framingForFrame helper.

Gates: lint 107 clean / 70 literals / 68 scenes green; vite build
294 modules; deterministic actor geometry smoke-tested (same seed same
vert count, hollow handling, fallback).

Co-Authored-By: Claude <noreply@anthropic.com>

flow-state/src/look/ArcDriver.js

@@ -816,6 +816,16 @@ export class ArcDriver {
         return null;
     }
 
+    /** Framing + personality for a frame, for the shared perspective rig. */
+    framingForFrame(frame) {
+        return this._framingAt(this._cueIndexAt(frame), frame);
+    }
+
+    personalityForFrame(frame, story) {
+        const s = story ?? (this.look.story ? storyStateAt(this.look.story, frame) : null);
+        return this._personalityAt(s);
+    }
+
     /** Push a palette change through without rebuilding layers. */
     setPalette(palette) {
         this.look.palette = palette;