hero: one wash for both themes — revert the continuous-blend machinery

Reverts the per-frame color sampling and luminance-blended wash modes:
the right fix was removing the second wash entirely. Cards now dim via
color multiply in both themes (hue-true; the light theme's alpha wash
toward the paper shifted footage pastel, and having two treatments is
what made theme fades show a mode switch at all). watchThemeColors
returns to the simple flip + settle double-derive.

Claude-Session: https://claude.ai/code/session_01YBoaBEt3gynzTwogBFtn4B

frontend/apps/artcraft-website-next/src/components/landing/hero-galaxy-tunables.ts

@@ -453,7 +453,7 @@ export const galaxyLookTuner = defineTunables("galaxyLook", "Galaxy look", {
     max: 1,
     step: 0.02,
     default: 1,
-    info: "Overall footage strength (dark theme dims via color, light theme washes via opacity).",
+    info: "Overall footage strength — dims via color multiply, the same in both themes.",
   },
   aberration: {
     label: "Dispersion",

frontend/apps/artcraft-website-next/src/components/landing/hero-galaxy.tsx

@@ -335,9 +335,9 @@ function GalaxyScene({
     boostCard: -1,
   });
 
-  // NOTE: no boolean dark flag — the light/dark wash treatment blends
-  // continuously by the LERPED background's luminance in the frame loop,
-  // so a theme fade never snaps between wash modes.
+  // One wash for both themes: cards dim via color multiply (hue-true —
+  // an alpha wash toward the paper shifted footage pastel in light mode,
+  // and two treatments meant a visible mode switch during theme fades).
 
   // One <video>, one shared texture, and one cover-fit window per clip.
   const videos = useMemo(
@@ -807,10 +807,6 @@ function GalaxyScene({
     cs.line.lerp(cs.tLine, themeK);
     lineMat.color.copy(cs.line);
     tickMat.color.copy(cs.line);
-    // Wash-mode blend: light theme washes cards via opacity, dark theme
-    // dims via color. Driven continuously by the LERPED background's
-    // luminance — a binary flag snapped the treatment mid-fade.
-    const darkK = smoothstep(1.95, 1.05, cs.bg.x + cs.bg.y + cs.bg.z);
 
     // Perf governor: EMA of the real frame time. Sustained drops below the
     // FPS floor shed cards (and their decode pressure) quickly; recovery
@@ -1241,12 +1237,8 @@ function GalaxyScene({
       u.uClickW.value = pt.clickWidth * Math.max(W, H);
       u.uRadius.value = Math.min(lk.cornerPx, H * 0.49);
       u.uFrameA.value = lk.frameAlpha;
-      const dimDark = lk.dim * solid + (1 - lk.dim * solid) * ck;
-      const wash = solid * Math.sqrt(lk.dim);
-      const alphaLight = lifecycle * waveK * (wash + (1 - wash) * ck);
-      const alphaDark = lifecycle * waveK;
-      u.uDim.value = 1 + (dimDark - 1) * darkK;
-      u.uAlpha.value = alphaLight + (alphaDark - alphaLight) * darkK;
+      u.uDim.value = lk.dim * solid + (1 - lk.dim * solid) * ck;
+      u.uAlpha.value = lifecycle * waveK;
 
       // A targeted card's clip outranks everything in the decode budget so
       // it plays immediately, wherever it is on the journey.

frontend/apps/artcraft-website-next/src/lib/theme-colors.ts

@@ -67,35 +67,28 @@ export function watchThemeColors(
   onChange: (colors: ThemeColors) => void,
 ): () => void {
   const derive = () => onChange(deriveThemeColors());
-  // Theme flips animate the tokens over 0.4s (see globals.css). Sampling
-  // just the endpoints left WebGL consumers chasing a stale target until
-  // the fade ended (a visible late shift); instead, sample the computed
-  // colors EVERY FRAME through the transition window so canvas layers
-  // track the DOM's animated tokens exactly.
-  let raf = 0;
-  let until = 0;
-  const sampleLoop = () => {
+  // Theme flips animate the tokens over 0.4s (see globals.css), so a
+  // derive at flip time reads MID-transition values. Deliver both: the
+  // immediate read (consumers that lerp start moving at once) and a final
+  // read after the fade settles so targets land on the true colors.
+  let settleTimer: ReturnType<typeof setTimeout> | undefined;
+  const deriveTwice = () => {
     derive();
-    if (performance.now() < until) raf = requestAnimationFrame(sampleLoop);
-  };
-  const onFlip = () => {
-    until = performance.now() + 550;
-    cancelAnimationFrame(raf);
-    derive();
-    raf = requestAnimationFrame(sampleLoop);
+    clearTimeout(settleTimer);
+    settleTimer = setTimeout(derive, 500);
   };
   derive();
 
-  const observer = new MutationObserver(onFlip);
+  const observer = new MutationObserver(deriveTwice);
   observer.observe(document.documentElement, {
     attributes: true,
     attributeFilter: ["data-theme"],
   });
   const mq = window.matchMedia("(prefers-color-scheme: dark)");
-  mq.addEventListener("change", onFlip);
+  mq.addEventListener("change", deriveTwice);
   return () => {
-    cancelAnimationFrame(raf);
+    clearTimeout(settleTimer);
     observer.disconnect();
-    mq.removeEventListener("change", onFlip);
+    mq.removeEventListener("change", deriveTwice);
   };
 }