feat: initialize Convert UI - browser-based file conversion app

- Add Next.js 16 with Turbopack and React 19
- Add Tailwind CSS 4 with OKLCH color system
- Implement FFmpeg.wasm for video/audio conversion
- Implement ImageMagick WASM for image conversion
- Add file upload with drag-and-drop
- Add format selector with fuzzy search
- Add conversion preview and download
- Add conversion history with localStorage
- Add dark/light theme support
- Support 22+ file formats across video, audio, and images

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

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

lib/wasm/wasmLoader.ts

@@ -0,0 +1,143 @@
+import type { FFmpeg } from '@ffmpeg/ffmpeg';
+import type { ConverterEngine, WASMModuleState } from '@/types/conversion';
+
+/**
+ * WASM module loading state
+ */
+const moduleState: WASMModuleState = {
+  ffmpeg: false,
+  imagemagick: false,
+  pandoc: false,
+};
+
+/**
+ * Cached WASM instances
+ */
+let ffmpegInstance: FFmpeg | null = null;
+let imagemagickInstance: any = null;
+let pandocInstance: any = null;
+
+/**
+ * Load FFmpeg WASM module
+ */
+export async function loadFFmpeg(): Promise<FFmpeg> {
+  if (ffmpegInstance && moduleState.ffmpeg) {
+    return ffmpegInstance;
+  }
+
+  try {
+    const { FFmpeg } = await import('@ffmpeg/ffmpeg');
+    const { toBlobURL } = await import('@ffmpeg/util');
+
+    ffmpegInstance = new FFmpeg();
+
+    // Load core and dependencies
+    const baseURL = 'https://unpkg.com/@ffmpeg/core@0.12.6/dist/umd';
+
+    ffmpegInstance.on('log', ({ message }) => {
+      console.log('[FFmpeg]', message);
+    });
+
+    await ffmpegInstance.load({
+      coreURL: await toBlobURL(`${baseURL}/ffmpeg-core.js`, 'text/javascript'),
+      wasmURL: await toBlobURL(`${baseURL}/ffmpeg-core.wasm`, 'application/wasm'),
+    });
+
+    moduleState.ffmpeg = true;
+    console.log('FFmpeg loaded successfully');
+
+    return ffmpegInstance;
+  } catch (error) {
+    console.error('Failed to load FFmpeg:', error);
+    throw new Error('Failed to load FFmpeg WASM module');
+  }
+}
+
+/**
+ * Load ImageMagick WASM module
+ */
+export async function loadImageMagick(): Promise<any> {
+  if (imagemagickInstance && moduleState.imagemagick) {
+    return imagemagickInstance;
+  }
+
+  try {
+    const ImageMagick = await import('@imagemagick/magick-wasm');
+
+    imagemagickInstance = ImageMagick;
+    moduleState.imagemagick = true;
+    console.log('ImageMagick loaded successfully');
+
+    return imagemagickInstance;
+  } catch (error) {
+    console.error('Failed to load ImageMagick:', error);
+    throw new Error('Failed to load ImageMagick WASM module');
+  }
+}
+
+/**
+ * Load Pandoc WASM module (placeholder for future implementation)
+ */
+export async function loadPandoc(): Promise<any> {
+  if (pandocInstance && moduleState.pandoc) {
+    return pandocInstance;
+  }
+
+  // TODO: Implement Pandoc WASM loading when available
+  // For now, throw an error
+  throw new Error('Pandoc WASM module is not yet implemented');
+}
+
+/**
+ * Get loaded module state
+ */
+export function getModuleState(): WASMModuleState {
+  return { ...moduleState };
+}
+
+/**
+ * Check if a specific module is loaded
+ */
+export function isModuleLoaded(engine: ConverterEngine): boolean {
+  return moduleState[engine];
+}
+
+/**
+ * Load appropriate WASM module for converter engine
+ */
+export async function loadModule(engine: ConverterEngine): Promise<any> {
+  switch (engine) {
+    case 'ffmpeg':
+      return loadFFmpeg();
+    case 'imagemagick':
+      return loadImageMagick();
+    case 'pandoc':
+      return loadPandoc();
+    default:
+      throw new Error(`Unknown converter engine: ${engine}`);
+  }
+}
+
+/**
+ * Unload all WASM modules and free memory
+ */
+export function unloadAll(): void {
+  if (ffmpegInstance) {
+    // FFmpeg doesn't have an explicit unload method
+    // Just null the instance
+    ffmpegInstance = null;
+    moduleState.ffmpeg = false;
+  }
+
+  if (imagemagickInstance) {
+    imagemagickInstance = null;
+    moduleState.imagemagick = false;
+  }
+
+  if (pandocInstance) {
+    pandocInstance = null;
+    moduleState.pandoc = false;
+  }
+
+  console.log('All WASM modules unloaded');
+}