feat: add Optimize for Web tool (#68)

* feat(image-engine): add OptimizeForWebOptions type

* feat(image-engine): add optimizeForWeb operation

* feat(shared): add optimize-for-web tool definition and i18n

* feat(api): add optimize-for-web route with preview endpoint

* feat(web): add optimize-for-web settings component with live preview

* feat(web): register optimize-for-web in tool registry

* fix(web): align toggle switch translate with codebase pattern

---------

Co-authored-by: stirling-image <stirling-image@users.noreply.github.com>

packages/image-engine/src/operations/optimize-for-web.ts

@@ -0,0 +1,43 @@
+import type { OptimizeForWebOptions, Sharp } from "../types.js";
+
+export async function optimizeForWeb(image: Sharp, options: OptimizeForWebOptions): Promise<Sharp> {
+  const {
+    format,
+    quality,
+    maxWidth,
+    maxHeight,
+    progressive = true,
+    stripMetadata = true,
+  } = options;
+
+  // Step 1: Resize if max dimensions are set
+  if (maxWidth || maxHeight) {
+    image = image.resize({
+      width: maxWidth,
+      height: maxHeight,
+      fit: "inside",
+      withoutEnlargement: true,
+    });
+  }
+
+  // Step 2: Preserve metadata only if requested
+  // Sharp strips metadata by default on output, so we only need to act
+  // when the user wants to KEEP metadata.
+  if (!stripMetadata) {
+    image = image.withMetadata();
+  }
+
+  // Step 3: Convert to target format with optimized settings
+  switch (format) {
+    case "webp":
+      return image.webp({ quality, effort: 4 });
+    case "jpeg":
+      return image.jpeg({ quality, progressive, mozjpeg: true });
+    case "avif":
+      return image.avif({ quality, effort: 4 });
+    case "png":
+      return image.png({ compressionLevel: 9, palette: true });
+    default:
+      throw new Error(`Unsupported format: ${format}`);
+  }
+}