feat: use shifter trainer scan flow

lib/pages/device_details_page.dart

@@ -10,8 +10,6 @@ import 'package:abawo_bt_app/util/bluetooth_settings.dart';
 import 'package:abawo_bt_app/widgets/bike_scan_dialog.dart';
 import 'package:abawo_bt_app/widgets/gear_ratio_editor_card.dart';
 import 'package:flutter/material.dart';
-import 'package:flutter_reactive_ble/flutter_reactive_ble.dart'
-    show DiscoveredDevice;
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
 import 'package:nb_utils/nb_utils.dart';
@@ -438,20 +436,6 @@ class _DeviceDetailsPageState extends ConsumerState<DeviceDetailsPage> {
       return;
     }
 
-    _isAssignTrainerDialogOpen = true;
-    final DiscoveredDevice? selectedBike;
-    try {
-      selectedBike = await BikeScanDialog.show(
-        context,
-        excludedDeviceId: widget.deviceAddress,
-      );
-    } finally {
-      _isAssignTrainerDialogOpen = false;
-    }
-    if (selectedBike == null || !mounted) {
-      return;
-    }
-
     await _startStatusStreamingIfNeeded();
     final shifter = _shifterService;
     if (shifter == null) {
@@ -463,8 +447,26 @@ class _DeviceDetailsPageState extends ConsumerState<DeviceDetailsPage> {
       );
       return;
     }
+    if (!mounted) {
+      return;
+    }
 
-    final result = await shifter.connectButtonToBike(selectedBike.id);
+    _isAssignTrainerDialogOpen = true;
+    final TrainerScanResult? selectedTrainer;
+    try {
+      selectedTrainer = await BikeScanDialog.show(
+        context,
+        shifter: shifter,
+      );
+    } finally {
+      _isAssignTrainerDialogOpen = false;
+    }
+    if (selectedTrainer == null || !mounted) {
+      return;
+    }
+
+    final result =
+        await shifter.connectButtonToTrainer(selectedTrainer.address);
     if (!mounted) {
       return;
     }
@@ -479,7 +481,13 @@ class _DeviceDetailsPageState extends ConsumerState<DeviceDetailsPage> {
     }
 
     ScaffoldMessenger.of(context).showSnackBar(
-      SnackBar(content: Text('Sent connect request for ${selectedBike.id}.')),
+      SnackBar(
+        content: Text(
+          selectedTrainer.name.isEmpty
+              ? 'Sent connect request for trainer.'
+              : 'Sent connect request for ${selectedTrainer.name}.',
+        ),
+      ),
     );
   }