Refactor search modes and optimize embedding generation

- Updated the dashboard template to hide the Code Graph Explorer feature.
- Enhanced the `executeCodexLens` function to use `exec` for better cross-platform compatibility and improved command execution.
- Changed the default `maxResults` and `limit` parameters in the smart search tool to 10 for better performance.
- Introduced a new `priority` search mode in the smart search tool, replacing the previous `parallel` mode, which now follows a fallback strategy: hybrid -> exact -> ripgrep.
- Optimized the embedding generation process in the embedding manager by batching operations and using a cached embedder instance to reduce model loading overhead.
- Implemented a thread-safe singleton pattern for the embedder to improve performance across multiple searches.

ccw/src/core/dashboard-generator.ts

@@ -173,6 +173,10 @@ function generateFromUnifiedTemplate(data: unknown): string {
   jsContent = jsContent.replace(/\{\{PROJECT_PATH\}\}/g, projectPath.replace(/\\/g, '/'));
   jsContent = jsContent.replace('{{RECENT_PATHS}}', JSON.stringify(recentPaths));
 
+  // Inject platform information for cross-platform MCP command generation
+  // 'win32' for Windows, 'darwin' for macOS, 'linux' for Linux
+  jsContent = jsContent.replace(/\{\{SERVER_PLATFORM\}\}/g, process.platform);
+
   // Inject JS and CSS into HTML template
   html = html.replace('{{JS_CONTENT}}', jsContent);
   html = html.replace('{{CSS_CONTENT}}', cssContent);