fix: QA sweep -- SSE crash, memory leaks, HEIC Docker decode, TGA detection, lint cleanup

- Fix SSE write-after-end crash in progress.ts (remove callback before ending stream)
- Fix blob URL memory leaks: revoke processedPreviewUrl and old HEIC preview URLs
- Add AbortController to batch fetch in use-tool-processor and use-pipeline-processor
- Fix TGA format misidentified as CUR (extension overrides magic bytes)
- Add libheif-plugin-libde265 to Docker for HEIC/HEIF decode support
- Remove unused imports and state (AppLayout, setSampledColor, useEffect)
- Fix non-null assertions in meme-text-renderer and meme-generator
- Fix confusing void type in meme-templates
- Remove unnecessary useEffect deps in adjustments-panel
- Fix Playwright strict mode violations in 5 E2E tests

apps/api/src/routes/progress.ts

@@ -254,12 +254,20 @@ export async function registerProgressRoutes(app: FastifyInstance): Promise<void
         listeners.set(jobId, new Set());
       }
 
+      let ended = false;
       const callback = (data: JobProgress | SingleFileProgress) => {
+        if (ended) return;
         sendEvent(data);
         if (
           ("status" in data && (data.status === "completed" || data.status === "failed")) ||
           ("phase" in data && (data.phase === "complete" || data.phase === "failed"))
         ) {
+          ended = true;
+          const subs = listeners.get(jobId);
+          if (subs) {
+            subs.delete(callback);
+            if (subs.size === 0) listeners.delete(jobId);
+          }
           reply.raw.end();
         }
       };