fix: resolve 7 bugs from QA sweep (#208)

- Fix selective metadata stripping (P1): use Sharp's keepExif()/keepIccProfile()
  instead of broken withMetadata({}) that preserved everything
- Fix meme font mapping (P1): add ArchivoBlack and ComicNeue fonts, map
  arial-black and comic-sans to correct TTF files instead of Anton
- Fix meme contentType (P2): detect actual output format from Sharp metadata
  instead of hardcoding image/png
- Fix info/text-overlay/color-palette i18n (P2): wire up existing translation
  keys that were imported but never used
- Fix info and color-palette displayMode (P2): change from before-after to
  no-comparison since neither tool produces a processed image
- Add missing i18n keys across all 21 locales
- Update displayMode test assertions

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

@@ -39,8 +39,8 @@ const FONT_DIR = join(import.meta.dirname, "../../static/fonts");
 
 const FONT_MAP: Record<string, string> = {
   anton: "Anton-Regular.ttf",
-  "arial-black": "Anton-Regular.ttf",
-  "comic-sans": "Anton-Regular.ttf",
+  "arial-black": "ArchivoBlack-Regular.ttf",
+  "comic-sans": "ComicNeue-Bold.ttf",
   montserrat: "Montserrat-Black.ttf",
   "bebas-neue": "BebasNeue-Regular.ttf",
   "permanent-marker": "PermanentMarker-Regular.ttf",

apps/api/src/routes/tools/meme-generator.ts

@@ -159,14 +159,22 @@ async function processMeme(
       .composite([{ input: svgBuffer }])
       .toBuffer();
   } else {
-    // No text -- just pass the image through
     result = await sharp(imageBuffer).toBuffer();
   }
 
+  const outputMeta = await sharp(result).metadata();
+  const detectedFormat = outputMeta.format ?? "png";
+  const mimeMap: Record<string, string> = {
+    jpeg: "image/jpeg",
+    png: "image/png",
+    webp: "image/webp",
+    gif: "image/gif",
+  };
+
   return {
     buffer: result,
     filename,
-    contentType: "image/png",
+    contentType: mimeMap[detectedFormat] ?? "image/png",
   };
 }