Initial commit: FieldLogger MAUI app with Maglink BLE support

Added Maglink RTK GNSS receiver integration with correct BLE UUIDs and device name filtering (ML-* prefix).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

README.md

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+# Field Logger
+
+Cross-platform .NET MAUI app (Windows, macOS, iOS, Android) for logging utility locate
+points from an **Underground Magnetics locating receiver** paired with RTK GPS positions
+from a **Maglink (H11) RTK receiver**, both over BLE.
+
+## Solution layout
+
+```
+FieldLogger/
+  Models/            Device protocol models (UmLogPacket, GnssFix) and DB entities (Job, LoggedPoint)
+  Services/
+    Ble/             BleSerialClient (line-oriented GATT serial) and BleScanner (Plugin.BLE)
+    UmReceiverService.cs      $UMPBDL protocol, PBDL schema-1 packet parsing
+    MaglinkService.cs         $GNPOS/$GNDEV NMEA parsing + AT commands
+    DeviceConnectionManager.cs  Auto-connect on launch, reconnect with backoff
+    PointLogger.cs            Joins locator packets with the latest GNSS fix, saves to SQLite
+    Data/AppDatabase.cs       sqlite-net-pcl store (jobs + points)
+    Sync/IMqttSyncService.cs  Stub for the future MQTT job/point synchronization
+  ViewModels/ + Views/        Shell tabs: Home, Jobs, Map, Settings (+ DeviceScan, JobDetail)
+  Resources/Raw/map.html      Google Maps JS page used by the Windows map view
+doc/                 Device protocol documentation
+```
+
+## How it works
+
+- **First launch:** the Home page redirects to the device scan page. Pick your locating
+  receiver (names starting with `UMRX` or `DT100`) and, from Settings or Home, the Maglink
+  RTK receiver. Selections are persisted.
+- **Subsequent launches:** `DeviceConnectionManager` auto-connects to both saved devices and
+  keeps retrying/reconnecting with backoff. Devices can be changed or forgotten in Settings.
+- **Logging:** create a job (Home or Jobs tab) — it becomes the active job. When the operator
+  presses the log button on the UM receiver, the app receives the PBDL packet, attaches the
+  most recent RTK fix (if fresher than 5 s), and stores the combined record with all metadata
+  in SQLite (`fieldlogger.db3` in app data).
+- **Map:** plots the active (or selected) job's points. Native map control on iOS/Android/macOS
+  (Google Maps on Android, Apple Maps on iOS/macOS); Google Maps JavaScript in a WebView on Windows.
+
+## Setup required before running
+
+1. **Google Maps key (Android):** replace `YOUR_GOOGLE_MAPS_ANDROID_API_KEY` in
+   `FieldLogger/Platforms/Android/AndroidManifest.xml` (Google Cloud Console → Maps SDK for Android).
+2. **Google Maps key (Windows):** create a Maps JavaScript API key and paste it into the
+   Settings page of the app.
+3. **Maglink GATT UUIDs:** the Maglink docs describe the serial protocol but not its GATT
+   table. `MaglinkService` currently assumes the Nordic UART Service
+   (`6e400001-b5a3-f393-e0a9-e50e24dcca9e`). Verify against the actual hardware (any BLE
+   scanner app will show the service UUIDs) and update the constants at the top of
+   `FieldLogger/Services/MaglinkService.cs` if they differ.
+
+## Building and running
+
+All commands are run from the repository root. (`dotnet run` does not support MAUI
+projects — use `dotnet build -t:Run` to deploy and launch instead.)
+
+### Windows
+
+```powershell
+# Build
+dotnet build FieldLogger/FieldLogger.csproj -f net9.0-windows10.0.19041.0
+
+# Run (unpackaged; WindowsPackageType=None)
+dotnet build FieldLogger/FieldLogger.csproj -f net9.0-windows10.0.19041.0 -t:Run
+# ...or launch the built exe directly:
+.\FieldLogger\bin\Debug\net9.0-windows10.0.19041.0\win10-x64\FieldLogger.exe
+```
+
+### Android
+
+```powershell
+# Build (APK is produced under bin/Debug/net9.0-android)
+dotnet build FieldLogger/FieldLogger.csproj -f net9.0-android
+
+# Deploy + launch on the connected device or running emulator
+dotnet build FieldLogger/FieldLogger.csproj -f net9.0-android -t:Run
+
+# If several devices/emulators are attached, pick one by adb serial (see `adb devices`)
+dotnet build FieldLogger/FieldLogger.csproj -f net9.0-android -t:Run -p:AdbTarget="-s emulator-5554"
+```
+
+Note: BLE does not work in the Android emulator — use a physical device
+(enable USB debugging, then `adb devices` to confirm it is attached).
+
+### iOS (requires a Mac; run these on the Mac, or from Windows via Visual Studio's paired Mac)
+
+```bash
+# Build
+dotnet build FieldLogger/FieldLogger.csproj -f net9.0-ios
+
+# Run in the default iOS Simulator (note: the simulator has no Bluetooth)
+dotnet build FieldLogger/FieldLogger.csproj -f net9.0-ios -t:Run
+
+# Run on a specific simulator by UDID (list with: xcrun simctl list devices)
+dotnet build FieldLogger/FieldLogger.csproj -f net9.0-ios -t:Run -p:_DeviceName=:v2:udid=<SIMULATOR_UDID>
+
+# Run on a physical iPhone (requires provisioning profile / signing set up in Xcode first)
+dotnet build FieldLogger/FieldLogger.csproj -f net9.0-ios -t:Run -p:RuntimeIdentifier=ios-arm64 -p:_DeviceName=<DEVICE_UDID>
+```
+
+### macOS (Mac Catalyst — requires a Mac)
+
+```bash
+# Build
+dotnet build FieldLogger/FieldLogger.csproj -f net9.0-maccatalyst
+
+# Build + launch
+dotnet build FieldLogger/FieldLogger.csproj -f net9.0-maccatalyst -t:Run
+```
+
+### Visual Studio
+
+Open `FieldLogger.sln`, pick the target framework/device in the debug-target dropdown,
+and press F5. This is the most convenient route for iOS from Windows (via a paired Mac)
+and for Android device debugging.
+
+## Roadmap
+
+- **MQTT sync** (`Services/Sync/IMqttSyncService.cs` is the seam): receive configured jobs
+  from the server and publish logged points. `Job.RemoteId` / `Synced` and
+  `LoggedPoint.Synced` columns are already in the schema. Suggested client: MQTTnet.
+- The Maglink can also upload positions directly via MQTT (`AT+UPLOADDATA_*` commands,
+  see `doc/AT_UPLOADDATA_MQTT_Configuration_EN.md`) if server-side ingestion is preferred.