Clickable previews: exact app deep-links everywhere

Every rendered still links to the app frame that produced it (song + seed + frame + venue/viz pins + probe warm-up, new window), via shared src/ui/preview.js. Supporting work, each measured: app honors ?frame/?venueSel/?viz/?warm= with pre-build pins (Show.applyPins) and primes deep-link loads; shared pinViz/pinVenueShell paths for gallery, filmstrip and app; probes prime and carry their warm-up; bank probes analyse the bank PCM and file decode is fixed-rate with bit-exact WAV parsing so app and probes see identical samples; materials built mid-update compile synchronously (needsCompile). Round trip verified bit-identical gallery-versus-app.

flow-state/src/engine/Layer.js

@@ -473,6 +473,19 @@ export class ModelLayer extends Layer {
             venueArrangement: this.venueArrangement ?? null,
             THREE,
         });
+        // Materials built mid-update (first update, satellite/passer rebuilds
+        // on discrete-count cuts, venue re-hangs) draw wrong until their
+        // programs link — up to ten frames on the heaviest scene, carried by
+        // feedback long after. Compiling synchronously here converts the
+        // rebuild frame from garbage to correct. Modules set
+        // instance.needsCompile = true wherever they (re)build geometry in
+        // update(); build()-time geometry is covered by prewarm instead.
+        if (this.instance && this.instance.needsCompile) {
+            this.instance.needsCompile = false;
+            try {
+                renderer.compileScene(this.scene, cam);
+            } catch { /* non-fatal: next warm-up frame converges anyway */ }
+        }
         renderer.renderScene(this.scene, cam, target, true);
     }