feat: add AVIF output format support across 6 remaining tools (#85)

Closes #73

AVIF was already supported in the core engine, convert, compress,
optimize-for-web, upscale, erase-object, svg-to-raster, and
pdf-to-image tools. This adds AVIF as an output format option to
the 6 tools that were missing it: split, collage, stitch,
image-to-base64, noise-removal, and red-eye-removal.

For each tool, both the frontend format selector (with quality
slider for AVIF's lossy encoding) and the backend Zod schema +
Sharp .avif() encoding were updated. AVIF defaults: quality from
the user slider, effort 4 (balanced encode speed).

Also fixes pre-existing Biome formatting violations in 5 files
that were blocking a clean lint pass.

apps/api/src/routes/tools/collage.ts

@@ -332,7 +332,7 @@ const settingsSchema = z.object({
   cornerRadius: z.number().min(0).max(500).default(0),
   backgroundColor: z.string().default("#FFFFFF"),
   aspectRatio: z.string().default("free"),
-  outputFormat: z.enum(["png", "jpeg", "webp"]).default("png"),
+  outputFormat: z.enum(["png", "jpeg", "webp", "avif"]).default("png"),
   quality: z.number().min(1).max(100).default(90),
 });
 
@@ -633,6 +633,10 @@ export function registerCollage(app: FastifyInstance) {
           pipeline = pipeline.webp({ quality: settings.quality });
           outputExt = "webp";
           break;
+        case "avif":
+          pipeline = pipeline.avif({ quality: settings.quality, effort: 4 });
+          outputExt = "avif";
+          break;
         default:
           pipeline = pipeline.png();
           outputExt = "png";