Add full-featured PyQt5 GUI with dark mode, persistent config, and SNI manager

[mrhx01]

Summary

This PR completely overhauls the user interface by introducing a modern PyQt5-based graphical application. It replaces the previous CLI + setup.py workflow with an intuitive tabbed interface, persistent configuration, dark mode support, and built-in SNI testing.

What's new / changed

• New GUI (gui.py): Fully responsive window with Configuration, SNI Pool, and Log tabs.
• Dark mode toggle: User can switch between light/dark themes.
• No more setup.py: Configuration is done directly in the GUI (default config created automatically).
• SNI pool management: Test SNIs, keep only working ones, add custom SNIs.
• Real-time logging & stats: Relay calls, failures, bytes relayed shown live.
• One-click operations: Install CA, test relay, scan Google IPs from GUI.
• Persistent configuration: All settings (including dark mode) saved to config.json.
• Improved launcher scripts: Both Windows (.bat) and Linux/macOS (.sh) now launch gui.py directly.
• New launchers: run-gui.bat and run-gui.sh provide one-click setup and execution for end users.

Why this is better

• User-friendly: Non-technical users can now configure and run the tunnel without touching a terminal.
• Faster iteration: No need to re-run setup wizard; all changes applied instantly.
• Professional look: Modern styling (light/dark) makes the tool more approachable.
• Maintainability: GUI code is self-contained; core proxy logic untouched.

Testing performed

• Tested on Windows 10/11 and Ubuntu 22.04 with Python 3.10–3.12.
• Proxy starts/stops correctly; SNI probing works; dark mode persists after restart.
• CA installation and removal via GUI buttons verified.

File changes summary

File	Type	Description
gui.py	added	Main GUI window (PyQt5)
scan_ips.py	added	Google IP scanner module
run-gui.bat	added	Windows launcher
run-gui.sh	added	Linux/macOS launcher
requirements.txt	modified	Added PyQt5, aiohttp

[onlymaj]

Hey @mrhx01, really nice effort on this, just sharing my own take, not a verdict. My worry is that PyQt5 is pretty heavy (around 80 - 120 MB) and won't run on the headless or Termux setups a lot of people use this tool from. Full disclosure, I'm biased here and also I have a parallel PR (#177) proposing a web dashboard instead. Curious what you and the maintainer think is the better direction.