feat: add tag picker in sensor calibration flow

lib/data/repositories/phoenix_sensor_repository.dart

@@ -80,6 +80,12 @@ class PhoenixSensorRepository implements SensorRepository {
     );
   }
 
+  @override
+  Future<int> setCalibrationTag(int id, String tagId) async {
+    final json = await client.setCalibrationTag(id, tagId);
+    return json['samples_needed'] as int;
+  }
+
   @override
   Future<void> cancelCalibration(int id) => client.cancelCalibration(id);
 

lib/data/repositories/sensor_repository.dart

@@ -32,6 +32,9 @@ abstract class SensorRepository {
   /// result. Returns the fitted (rssiRef, pathLossExp) pair.
   Future<({double rssiRef, double pathLossExp})> finishCalibration(int id);
 
+  /// Commits a specific tag for calibration stages. Returns samples_needed.
+  Future<int> setCalibrationTag(int id, String tagId);
+
   /// Aborts calibration and discards all accumulated stage data.
   Future<void> cancelCalibration(int id);