feat: cross-platform NetFinder for CS203XL discovery on iOS/Android/Windows

[mephist-cne]

Summary

Adds CSLibrary.NetFinder.NetFinder for discovering CS203XL readers over UDP (port 3000) on Windows, Android, and iOS.

What changed

NEW: Source/Properties/AndroidPermissions.cs

• [assembly: Android.Runtime.UsesPermission] attributes for:
  • ACCESS_WIFI_STATE, ACCESS_NETWORK_STATE, CHANGE_WIFI_MULTICAST_STATE, INTERNET — required for NetFinder UDP broadcast on Android
  • BLUETOOTH_* permissions — Plugin.BLE coverage
• Only compiles when targeting Android (#if ANDROID)

NEW: Source/HAL/TCPIP/NetFinder.cs — CSLibrary.NetFinder namespace

• Wraps CSLibrary.NetFinder.CS203XL.NetFinder (UDP port 3000)
• Singleton pattern, static SearchDevice() / StopSearch() / ClearDeviceList()
• OnSearchCompleted event with DeviceFinderArgs (IP, MAC, name, port)

MODIFIED: Source/HAL/TCPIP/ClassDeviceFinder.cs

• Changed #if __MwwmCrossPluginBLE → #if TCP
• Removed Windows-only DeviceWatcher code
• Now wires DeviceFinder.SearchDevice() → CSLibrary.NetFinder.NetFinder

MODIFIED: Source/CSLibrary.cs

• Added using CSLibrary.NetFinder;

MODIFIED: CSLibrary2026.csproj TargetFrameworks

• Added: net10.0-android, net10.0-ios, net10.0-maccatalyst

Usage (MAUI app)

using CSLibrary.NetFinder;

// Discover CS203XL devices (UDP broadcast port 3000)
NetFinder.SearchDevice();
NetFinder.OnSearchCompleted += (s, e) => {
    Console.WriteLine($"Found: {e.IPAddress}, {e.DeviceName}");
};

// Connect
var reader = new CSLibrary.RFIDReader.ClassRFID();
await reader.ConnectAsync(e.IPAddress, 5000);  // TCP port 5000

Platform Notes

• Windows: ✅ NetFinder UDP broadcast works natively
• Android: ✅ Requires ACCESS_WIFI_STATE, CHANGE_WIFI_MULTICAST_STATE — declared via assembly attributes in this PR; also add to your app AndroidManifest.xml as fallback
• iOS: ⚠️ Apple blocks UDP multicast/broadcast at OS level — NetFinder will not work on iOS without a network permission entitlement (rarely approved by Apple)

Next Steps

• Merge PR, publish 1.0.0-beta.3 to NuGet from Windows/macOS build machine with Android/iOS SDKs