Add debug HTTP server for remote monitoring

Starts an HTTP server on port 9868 (configurable via debug_port.txt)
when debug_token.txt exists in the app runtime directory. Provides
/health, /log, /status, and /items endpoints for live monitoring.
Token-based auth required.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "real-debrid-downloader",
-  "version": "1.4.75",
+  "version": "1.4.76",
   "description": "Real-Debrid Downloader Desktop (Electron + React + TypeScript)",
   "main": "build/main/main/main.js",
   "author": "Sucukdeluxe",