feat: Gluetun VPN integration and remote service enhancements

Major features:
- Native Docker-based Gluetun VPN proxy provider with multi-provider support
  (NordVPN, Windscribe, Surfshark, ExpressVPN, and 50+ more)
- Stateless remote service architecture with local session caching
- Client-side authentication for remote services (browser, 2FA, OAuth support)

Key changes:
- core/proxies/windscribevpn.py: Enhanced proxy handling
- core/crypto.py: Cryptographic utilities
- docs/VPN_PROXY_SETUP.md: Comprehensive VPN/proxy documentation

pyproject.toml

@@ -88,7 +88,6 @@ dev = [
     "types-requests>=2.31.0.20240406,<3",
     "isort>=5.13.2,<8",
     "ruff>=0.3.7,<0.15",
-    "unshackle",
 ]
 
 [tool.hatch.build.targets.wheel]