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/lib/file-validation.ts

@@ -221,8 +221,8 @@ export async function validateImageBuffer(
     detectedFormat = "raw";
   }
 
-  // TGA has no magic bytes — detect by extension only
-  if (!detectedFormat && ext === "tga") {
+  // TGA has no magic bytes and its header can match other formats (e.g. CUR)
+  if (ext === "tga") {
     detectedFormat = "tga";
   }
 

apps/api/src/lib/meme-text-renderer.ts

@@ -56,9 +56,8 @@ const fontCache = new Map<string, opentype.Font>();
 export function loadFont(family: string): opentype.Font {
   const filename = FONT_MAP[family] ?? FONT_MAP.anton;
 
-  if (fontCache.has(filename)) {
-    return fontCache.get(filename)!;
-  }
+  const cached = fontCache.get(filename);
+  if (cached) return cached;
 
   const buf = readFileSync(join(FONT_DIR, filename));
   let font: opentype.Font;