fix(assets): give the frame sheets a build-stamped URL, so a replaced sheet stops arriving from cache

docker/frontend/src/engine/assets.ts

@@ -18,6 +18,16 @@ export const MARK_FACES: { family: string; file: string }[] = [
   { family: 'Fraunces', file: '/assets/Fraunces-Regular.ttf' },
 ];
 
+// The two frame sheets are drawn by hand and dropped over the file of the same
+// name, and that name is the one thing neither cache lets go of: nginx answers
+// /assets/ immutable for 30 days (nginx.conf) and the service worker serves the
+// path cache-first (sw.js) — both stored for the sheet that was there the day the
+// visitor first loaded the app, so a sheet swapped in today arrives as yesterday's.
+// The build stamp in the query is what makes the URL move with the build; the old
+// entry stays in both caches, unasked for, and ages out on its own.
+const ART = `?v=${import.meta.env.VITE_VERSION ?? ''}`;
+
+// The fonts never change under a build, so they keep the plain URL.
 async function buf(url: string): Promise<ArrayBuffer> {
   const res = await fetch(url);
   if (!res.ok) throw new Error(`fetch ${url}: ${res.status}`);
@@ -37,8 +47,8 @@ export async function loadEngine(): Promise<{ assets: RenderAssets; gpu: boolean
     const [textFont, emojiFont, wallframePng, oldFilmPng, markFonts] = await Promise.all([
       buf('/assets/Cousine-Regular.ttf'),
       buf('/assets/NotoEmoji-GPS.ttf'),
-      buf('/assets/wallframe.png'),
-      buf('/assets/old_film.png'),
+      buf(`/assets/wallframe.png${ART}`),
+      buf(`/assets/old_film.png${ART}`),
       Promise.all(MARK_FACES.map(async (face) => ({ family: face.family, bytes: await buf(face.file) }))),
     ]);
     assets = {