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/templates/dashboard-js/utils.js

@@ -5,6 +5,37 @@
 
 // ========== HTML/Text Processing ==========
 
+/**
+ * Encode JSON config data to Base64 for safe HTML attribute storage
+ * @param {Object} config - Configuration object to encode
+ * @returns {string} Base64 encoded JSON string
+ */
+function encodeConfigData(config) {
+  try {
+    const jsonStr = JSON.stringify(config);
+    return btoa(encodeURIComponent(jsonStr));
+  } catch (err) {
+    console.error('[Utils] Error encoding config data:', err);
+    return '';
+  }
+}
+
+/**
+ * Decode Base64 config data back to JSON object
+ * @param {string} encoded - Base64 encoded string
+ * @returns {Object|null} Decoded configuration object or null on error
+ */
+function decodeConfigData(encoded) {
+  try {
+    if (!encoded) return null;
+    const jsonStr = decodeURIComponent(atob(encoded));
+    return JSON.parse(jsonStr);
+  } catch (err) {
+    console.error('[Utils] Error decoding config data:', err);
+    return null;
+  }
+}
+
 /**
  * Escape HTML special characters to prevent XSS attacks
  * @param {string} str - String to escape