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

server/helpers/rateLimit.helpers.js

@@ -1,14 +1,24 @@
 const RateLimit = require("express-rate-limit");
 
 
-/* Rate Limite */
-const rateLimite = RateLimit({
+/**
+ * Rate limiter middleware used to protect public endpoints
+ * against abusive or excessive requests.
+ *
+ * Restrictions:
+ * - 5 requests per IP address
+ * - 15-minute sliding window
+ *
+ * When the limit is exceeded, a HTTP 429 (Too Many Requests)
+ * response is returned.
+ */
+const rateLimit = RateLimit({
   windowMs: 15 * 60 * 1000, // 15 minutes
-  max: 5, // limit each IP to 100 requests per windowMs on the root path
+  max: 5,
   message: "Too many requests, please try again later.",
-  statusCode: 429, // HTTP status code for "Too Many Requests"
+  statusCode: 429,
 });
 
 module.exports = {
-    rateLimite
+    rateLimit
 }