feat: ui rework and gear generator

lib/widgets/gear_ratio_editor_card.dart

@@ -1,5 +1,7 @@
 import 'dart:math' as math;
 
+import 'package:abawo_bt_app/model/gear_ratio_codec.dart';
+import 'package:abawo_bt_app/widgets/gear_configurator_dialog.dart';
 import 'package:flutter/material.dart';
 
 class GearRatioPreset {
@@ -76,8 +78,8 @@ class GearRatioEditorCard extends StatefulWidget {
 }
 
 class _GearRatioEditorCardState extends State<GearRatioEditorCard> {
-  static const double _sliderMin = 0.10;
-  static const double _sliderMax = 3.90;
+  static const double _sliderMin = gearRatioMin;
+  static const double _sliderMax = gearRatioMax;
   static const double _sliderPivotT = 0.50;
   static const double _sliderPivotV = 1.00;
   static const Duration _animDuration = Duration(milliseconds: 280);
@@ -165,10 +167,22 @@ class _GearRatioEditorCardState extends State<GearRatioEditorCard> {
                           TextStyle(fontSize: 17, fontWeight: FontWeight.w700),
                     ),
                   ),
+                  if (!_isEditing)
+                    IconButton(
+                      tooltip: 'Configure drivetrain',
+                      onPressed: (widget.isLoading ||
+                              widget.errorText != null ||
+                              _isSaving)
+                          ? null
+                          : _openGearConfigurator,
+                      icon: const Icon(Icons.settings_input_component_outlined),
+                    ),
                   if (!_isEditing)
                     IconButton(
                       tooltip: 'Edit ratios',
-                      onPressed: (widget.isLoading || widget.errorText != null)
+                      onPressed: (widget.isLoading ||
+                              widget.errorText != null ||
+                              _isSaving)
                           ? null
                           : _enterEditMode,
                       icon: const Icon(Icons.edit_outlined),
@@ -830,6 +844,62 @@ class _GearRatioEditorCardState extends State<GearRatioEditorCard> {
     _loadPreset(selected);
   }
 
+  Future<void> _openGearConfigurator() async {
+    final calculation = await showGearConfiguratorDialog(context);
+    if (!mounted || calculation == null) {
+      return;
+    }
+
+    setState(() {
+      _isSaving = true;
+    });
+
+    final ratios = List<double>.from(calculation.ratios);
+    final message =
+        await widget.onSave(ratios, _normalizeDefaultIndex(0, ratios.length));
+    if (!mounted) {
+      return;
+    }
+
+    setState(() {
+      _isSaving = false;
+      if (message == null) {
+        _committed = ratios;
+        _draft = List<double>.from(ratios);
+        _committedDefaultGearIndex = _normalizeDefaultIndex(0, ratios.length);
+        _draftDefaultGearIndex = _committedDefaultGearIndex;
+        _isEditing = false;
+        _isExpanded = true;
+      }
+    });
+
+    final messenger = ScaffoldMessenger.of(context);
+    if (message != null) {
+      messenger.showSnackBar(SnackBar(content: Text(message)));
+      return;
+    }
+
+    final notices = <String>[
+      if (calculation.discardedBelowRange > 0)
+        '${calculation.discardedBelowRange} below range skipped',
+      if (calculation.discardedAboveRange > 0)
+        '${calculation.discardedAboveRange} above range skipped',
+      if (calculation.duplicateCount > 0)
+        '${calculation.duplicateCount} duplicates removed',
+      if (calculation.truncatedCount > 0)
+        '${calculation.truncatedCount} high gears truncated',
+    ];
+    messenger.showSnackBar(
+      SnackBar(
+        content: Text(
+          notices.isEmpty
+              ? 'Applied ${ratios.length} calculated gear ratios.'
+              : 'Applied ${ratios.length} calculated gear ratios (${notices.join(', ')}).',
+        ),
+      ),
+    );
+  }
+
   void _applyNamedPreset(String name) {
     for (final preset in widget.presets) {
       if (preset.name.toLowerCase() == name.toLowerCase()) {
@@ -995,8 +1065,7 @@ class _GearRatioEditorCardState extends State<GearRatioEditorCard> {
   }
 
   double _quantizeRatio(double raw) {
-    final clamped = raw.clamp(_sliderMin, _sliderMax);
-    return ((clamped * 64).round() / 64.0).clamp(_sliderMin, _sliderMax);
+    return quantizeGearRatio(raw).clamp(_sliderMin, _sliderMax);
   }
 
   (List<double>, int) _sortedWithDefault(