fix: implement actual ImageMagick WASM conversion with quality settings

Previously, the ImageMagick service was just a placeholder that returned
the input data unchanged. This caused PNG to WebP conversions to have
the same file size.

Changes:
- Properly implement ImageMagick.read() with conversion logic
- Apply imageQuality option to control compression
- Apply imageWidth/imageHeight options with aspect ratio preservation
- Use correct MagickFormat enum values for output formats
- Fix write() method signature (format comes before callback)
- Remove unnecessary initializeImageMagick() call

Image conversion now properly applies:
- Quality settings (1-100%)
- Resolution/resize options
- Format-specific compression

This fixes the issue where quality settings had no effect on output
file size. Users will now see proper file size reduction when using
lower quality settings or converting to compressed formats like WebP.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

lib/converters/imagemagickService.ts

@@ -14,7 +14,7 @@ export async function convertWithImageMagick(
 
   try {
     // Load ImageMagick instance
-    const ImageMagick = await loadImageMagick();
+    await loadImageMagick();
 
     // Report initial progress
     if (onProgress) onProgress(10);
@@ -26,21 +26,55 @@ export async function convertWithImageMagick(
     if (onProgress) onProgress(30);
 
     // Import ImageMagick functions
-    const IM = await import('@imagemagick/magick-wasm');
+    const { ImageMagick } = await import('@imagemagick/magick-wasm');
 
-    // Determine output format
-    const magickFormat = getMagickFormat(outputFormat);
+    if (onProgress) onProgress(40);
+
+    // Get output format enum
+    const outputFormatEnum = await getMagickFormatEnum(outputFormat);
 
     if (onProgress) onProgress(50);
 
-    // Convert image - Note: This is a placeholder implementation
-    // The actual ImageMagick WASM API may differ
-    const result = inputData; // Placeholder: just return input for now
+    // Convert image using ImageMagick
+    let result: Uint8Array;
 
-    if (onProgress) onProgress(90);
+    await ImageMagick.read(inputData, (image) => {
+      // Apply quality setting if specified
+      if (options.imageQuality !== undefined) {
+        image.quality = options.imageQuality;
+      }
+
+      // Apply resize if specified
+      if (options.imageWidth || options.imageHeight) {
+        const width = options.imageWidth || 0;
+        const height = options.imageHeight || 0;
+
+        if (width > 0 && height > 0) {
+          // Both dimensions specified
+          image.resize(width, height);
+        } else if (width > 0) {
+          // Only width specified, maintain aspect ratio
+          const aspectRatio = image.height / image.width;
+          image.resize(width, Math.round(width * aspectRatio));
+        } else if (height > 0) {
+          // Only height specified, maintain aspect ratio
+          const aspectRatio = image.width / image.height;
+          image.resize(Math.round(height * aspectRatio), height);
+        }
+      }
+
+      if (onProgress) onProgress(70);
+
+      // Write to output format
+      image.write(outputFormatEnum, (data) => {
+        result = data;
+      });
+
+      if (onProgress) onProgress(90);
+    });
 
     // Create blob from result
-    const blob = new Blob([result as BlobPart], { type: getMimeType(outputFormat) });
+    const blob = new Blob([result! as BlobPart], { type: getMimeType(outputFormat) });
 
     if (onProgress) onProgress(100);
 
@@ -65,20 +99,21 @@ export async function convertWithImageMagick(
 /**
  * Get ImageMagick format enum
  */
-function getMagickFormat(format: string): any {
-  // This is a placeholder - actual implementation would use MagickFormat enum
-  const formatMap: Record<string, string> = {
-    png: 'Png',
-    jpg: 'Jpeg',
-    jpeg: 'Jpeg',
-    webp: 'WebP',
-    gif: 'Gif',
-    bmp: 'Bmp',
-    tiff: 'Tiff',
-    svg: 'Svg',
+async function getMagickFormatEnum(format: string): Promise<any> {
+  const { MagickFormat } = await import('@imagemagick/magick-wasm');
+
+  const formatMap: Record<string, any> = {
+    png: MagickFormat.Png,
+    jpg: MagickFormat.Jpg,
+    jpeg: MagickFormat.Jpg,
+    webp: MagickFormat.WebP,
+    gif: MagickFormat.Gif,
+    bmp: MagickFormat.Bmp,
+    tiff: MagickFormat.Tiff,
+    svg: MagickFormat.Svg,
   };
 
-  return formatMap[format.toLowerCase()] || format;
+  return formatMap[format.toLowerCase()] || MagickFormat.Png;
 }
 
 /**