Venues: persistent room, motivated camera, ride; drop Pylon Grid

- Venue as one continuous place: persistent per-song layer, interpolated
  venueState, story jumps (one re-hang max + recap) with camera cuts
- Room camera shot plan (venueShots.js): per-section size/target, monotonic
  look sweep, traverse glide body, room-side alternation
- New Ride venue: generated vehicle + actor passengers, radio RTT screen,
  chase/stationary modes, ride archetype across generator/camera/staging
- Flora cost trim (5x(12+6+6) -> 4x(8+4+4) SDF evals, 204ms -> 140ms worst)
- Delete Pylon Grid shader (2.5s/frame SwiftShader); drop its metadata row
- tools/venue-check.js headless gate harness + venue-gallery explorer

flow-state/src/engine/Layer.js

@@ -145,6 +145,7 @@ export class Layer {
         this.blend = blend;
         this.palette = [];
         this.personality = null;
+        this.venueState = null;
     }
 
     /**
@@ -374,6 +375,7 @@ export class ModelLayer extends Layer {
         this.camera = new THREE.PerspectiveCamera(60, 16 / 9, 0.1, 200);
         this.camera.position.set(0, 0, 5);
         this.actorSpec = options.actorSpec || null;
+        this.venueSpec = options.venueSpec || null;
         // Shared rig injected by Compositor at render time when available.
         this.sharedCamera = null;
         this.instance = this.module.build({
@@ -382,10 +384,48 @@ export class ModelLayer extends Layer {
             seed: this.seed,
             params: this.baseParams,
             actorSpec: this.actorSpec,
+            venueSpec: this.venueSpec,
             THREE,
         });
     }
 
+    /** Allow the look to swap the venue without rebuilding the layer. */
+    setVenue(venueSpec) {
+        this.venueSpec = venueSpec || null;
+        return this;
+    }
+
+    /**
+     * Bind the composited viz texture onto this layer's screen (venue RTT).
+     * No-op unless the module implements bindVizTexture(instance, texture).
+     * Delegating keeps venue materials owned by the venue module — the
+     * compositor never touches venue meshes directly.
+     */
+    bindVizTexture(texture) {
+        if (this.module && typeof this.module.bindVizTexture === 'function' && this.instance) {
+            this.module.bindVizTexture(this.instance, texture);
+        }
+        return this;
+    }
+
+    /**
+     * Base wash for the viz composite. The shot is keyed over this colour
+     * instead of over black: a shot floating on black is the composition
+     * failure the phase 12 rules forbid, miniaturised onto the venue screen —
+     * and it measured ~5x the no-venue section distance (sparse bright things
+     * on nothing maximise layout/region jumps). Defaults to a dark neutral;
+     * venue modules override via washColor(instance) to match their room.
+     */
+    washColor() {
+        try {
+            if (this.module && typeof this.module.washColor === 'function' && this.instance) {
+                const c = this.module.washColor(this.instance);
+                if (Array.isArray(c) && c.length >= 3) return [c[0], c[1], c[2]];
+            }
+        } catch { /* fall through to default */ }
+        return [0.03, 0.03, 0.04];
+    }
+
     /** Allow the look to swap the actor without rebuilding the layer. */
     setActor(actorSpec) {
         this.actorSpec = actorSpec || null;
@@ -418,6 +458,13 @@ export class ModelLayer extends Layer {
             framing: this.framing,
             opacity: this.opacity,
             actorSpec: this.actorSpec,
+            venueSpec: this.venueSpec,
+            venueState: this.venueState,
+            // Song-level arrangement salt (see ArcDriver.venueJumpAt): which
+            // dressing of the room is live. Null most of the time; the module
+            // re-hangs only when it changes. Plain field, not on Layer base —
+            // only venue modules read it.
+            venueArrangement: this.venueArrangement ?? null,
             THREE,
         });
         renderer.renderScene(this.scene, cam, target, true);