feat(xtream-proxy): rewrite proxy logic and update configuration format

Refactor the xtream-proxy from a single-file Express-based server to a
modular Node.js application using native http/https modules. This
change introduces a major version bump to 2.0.0.

- Replace `hosts.txt` with `upstreams.json` for configuration
- Remove heavy dependencies (`express`, `ws`) in favor of native modules
- Implement new environment variables for proxy credentials and timeouts
- Add `src/` directory for modular code structure
- Add `docker-compose.example.yml` for easier deployment
- Update Dockerfile to support the new directory structure and environment
- Improve error handling and probe logic for upstream selection

Dockers/xtream-proxy/.dockerignore

@@ -1,3 +1,5 @@
 node_modules
 npm-debug.log
-hosts.txt.example
+upstreams.json
+upstreams.json.example
+.git