[WIP] Add SOCKS5 proxy server implementation in Android app

[Copilot]

• Set up Android project structure (Gradle, manifest, build files)
• Create SOCKS5 server implementation (Socks5Server.kt, Socks5Handler.kt)
• Create ForegroundService (ProxyForegroundService.kt)
• Create ViewModel (ProxyViewModel.kt)
• Create Compose UI (ProxyScreen.kt, MainActivity.kt, Theme)
• Create AndroidManifest.xml with proper permissions
• Create notification icon and resources
• Add GitHub Actions CI workflow
• Validate build compiles successfully via CI

Original prompt

You are a senior Android developer. Build a complete Android application in Kotlin that works as a SOCKS5 proxy server running locally on the device.

Core Requirements:

1. The app must start a SOCKS5 proxy server bound to 0.0.0.0 (all interfaces) on a configurable port.
2. The server must support:
   • SOCKS5 protocol (RFC 1928)
   • TCP CONNECT command
   • Optional username/password authentication (RFC 1929)
3. The proxy must tunnel traffic between client and destination (full duplex stream forwarding).
4. The server must handle multiple concurrent connections using coroutines.

Networking:

• Use Kotlin + coroutines (no blocking IO)
• Use ServerSocket or NIO
• Efficient buffer forwarding between client and remote host
• Proper error handling and socket closing

Android Constraints:

• Run the proxy inside a Foreground Service
• Show persistent notification when running
• Handle lifecycle correctly (start/stop server)
• Request INTERNET permission
• Support Android 8+ (API 26+)

UI Requirements:

Create a simple UI with:

• Toggle button: Start / Stop server
• Input field: Port
• Switch: Enable authentication
• Input fields: Username and Password (visible only if auth enabled)
• Status indicator (Running / Stopped)

Use:

• Jetpack Compose for UI
• ViewModel for state management

Architecture:

• Clean architecture (UI / Service / Network layer)
• Separate SOCKS5 protocol logic into its own class/module
• Use dependency injection (Hilt preferred but optional)

SOCKS5 Implementation Details:

Implement:

1. Greeting:

   • Version = 0x05
   • Method negotiation (no auth or username/password)

2. Authentication (if enabled):

   • Version 0x01
   • Validate credentials

3. Request:

   • CONNECT command only
   • Support IPv4, domain names

4. Response:

   • Proper success and error replies

Extra:

• Log connections (client IP, target host)
• Gracefully handle invalid packets
• Prevent crashes on malformed input

Deliverables:

• Full Android project structure
• MainActivity
• ForegroundService implementation
• SOCKS5 server implementation
• UI code (Compose)
• Manifest setup

Important:

• Do NOT use third-party SOCKS libraries. Implement protocol manually.
• Write clean, well-commented code.
• Ensure the app is functional and can be built immediately.