refactor: add full documentation and fix theme loading robustness

- Add JSDoc comments across frontend and backend modules
- Improve code readability and maintainability with consistent documentation style
- Document Electron IPC handlers, UI utilities, and theme system
- Add missing function/class documentation in theme loader and app services
- Minor structural improvements and cleanup across Electron main process modules
- Minor fixes on variable names

config.js

@@ -3,43 +3,107 @@ const { app } = require("electron");
 const fs = require("fs");
 const path = require("path");
 
-
+/**
+ * Indicates whether the application is running in development mode.
+ * Determined by Electron's packaging state.
+ */
 const devMode = !app.isPackaged;
 
-
+/**
+ * Resolves the configuration file path depending on runtime environment.
+ *
+ * In development:
+ * - Uses local config/config.dev.json
+ * - Creates it from default if missing
+ *
+ * In production:
+ * - Uses app userData/config.json
+ * - Creates it from bundled default config if missing
+ *
+ * @returns {string} Absolute path to the active configuration file
+ */
 function resolveConfigPath() {
   if (devMode) {
     const devConfigPath = path.join(__dirname, "config", "config.dev.json");
+
     if (!fs.existsSync(devConfigPath)) {
-      const defaultConfigPath = path.join(__dirname, "config", "config.default.json");
+      const defaultConfigPath = path.join(
+        __dirname,
+        "config",
+        "config.default.json"
+      );
       fs.copyFileSync(defaultConfigPath, devConfigPath);
     }
+
     return devConfigPath;
   }
 
   const userConfigPath = path.join(app.getPath("userData"), "config.json");
+
   if (!fs.existsSync(userConfigPath)) {
-    const defaultConfigPath = path.join(process.resourcesPath, "config", "config.default.json");
+    const defaultConfigPath = path.join(
+      process.resourcesPath,
+      "config",
+      "config.default.json"
+    );
     fs.copyFileSync(defaultConfigPath, userConfigPath);
   }
 
   return userConfigPath;
 }
 
+/**
+ * Path to the active configuration file used at runtime.
+ */
 const featuresPath = resolveConfigPath();
 
+/**
+ * Loads and parses the feature configuration file.
+ *
+ * @returns {Object} Parsed feature flags configuration
+ * @throws {Error} If the configuration file is missing or invalid
+ */
 function loadFeatures() {
   const raw = fs.readFileSync(featuresPath, "utf-8");
   return JSON.parse(raw);
 }
 
+/**
+ * In-memory snapshot of application feature flags.
+ *
+ * Note: Changes to the config file are not automatically reflected.
+ * A restart or reload is required.
+ */
 const configFeatures = loadFeatures();
 
 module.exports = {
+  /**
+   * Application version from package.json
+   */
   version: packageJson.version,
+
+  /**
+   * Backend Express / internal server port
+   */
   applicationPort: "8787",
+
+  /**
+   * Indicates whether the app is running in development mode
+   */
   devMode,
+
+  /**
+   * Discord RPC application identifier
+   */
   DiscordRPCID: "1410934537051181146",
+
+  /**
+   * Runtime feature flags loaded from configuration file
+   */
   configFeatures,
-  featuresPath
-}
+
+  /**
+   * Path to the active configuration file
+   */
+  featuresPath,
+};