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/tools/meme-generator.ts

@@ -260,7 +260,10 @@ export function registerMemeGenerator(app: FastifyInstance) {
     // ── Process ─────────────────────────────────────────────────────
     try {
       // Normalize the image for Sharp compatibility
-      imageBuffer = await autoOrient(await ensureSharpCompat(imageBuffer!));
+      if (!imageBuffer) {
+        return reply.status(400).send({ error: "No image provided" });
+      }
+      imageBuffer = await autoOrient(await ensureSharpCompat(imageBuffer));
 
       const output = await processMeme(imageBuffer, settings, filename, templateTextBoxes);