Dive planner Phase 3: Live Profile Canvas UI and cutover

lib/core/router/app_router.dart

@@ -116,7 +116,7 @@ import 'package:submersion/features/dive_computer/presentation/providers/downloa
 import 'package:submersion/features/dive_log/presentation/providers/dive_computer_providers.dart';
 import 'package:submersion/features/import_wizard/data/adapters/dive_computer_adapter.dart';
 import 'package:submersion/features/dashboard/presentation/pages/dashboard_page.dart';
-import 'package:submersion/features/dive_planner/presentation/pages/dive_planner_page.dart';
+import 'package:submersion/features/planner/presentation/pages/plan_canvas_page.dart';
 import 'package:submersion/features/surface_interval_tool/presentation/pages/surface_interval_tool_page.dart';
 import 'package:submersion/features/import_wizard/data/adapters/universal_adapter.dart';
 import 'package:submersion/l10n/l10n_extension.dart';
@@ -206,12 +206,12 @@ final appRouterProvider = Provider<GoRouter>((ref) {
                   GoRoute(
                     path: 'dive-planner',
                     name: 'divePlanner',
-                    builder: (context, state) => const DivePlannerPage(),
+                    builder: (context, state) => const PlanCanvasPage(),
                     routes: [
                       GoRoute(
                         path: ':planId',
                         name: 'editPlan',
-                        builder: (context, state) => DivePlannerPage(
+                        builder: (context, state) => PlanCanvasPage(
                           planId: state.pathParameters['planId'],
                         ),
                       ),

lib/features/dive_planner/presentation/providers/dive_planner_providers.dart

@@ -193,19 +193,34 @@ class DivePlanNotifier extends StateNotifier<DivePlanState> {
     }
   }
 
-  /// Add a simple dive profile (descent + bottom + ascent).
+  /// Add a simple dive profile as the bottom portion only: a descent and a
+  /// bottom segment. The ascent and any decompression are always computed by
+  /// the PlanEngine from the deepest segment, so authoring a fixed ascent
+  /// here would suppress real deco stops.
   void addSimplePlan({
     required double maxDepth,
     required int bottomTimeMinutes,
   }) {
     if (state.tanks.isEmpty) return;
 
     final tank = state.tanks.first;
-    final segments = _calculator.createSimplePlan(
-      maxDepth: maxDepth,
-      bottomTimeMinutes: bottomTimeMinutes,
-      tank: tank,
-    );
+    final segments = <PlanSegment>[
+      PlanSegment.descent(
+        id: _uuid.v4(),
+        targetDepth: maxDepth,
+        tankId: tank.id,
+        gasMix: tank.gasMix,
+        order: 0,
+      ),
+      PlanSegment.bottom(
+        id: _uuid.v4(),
+        depth: maxDepth,
+        durationMinutes: bottomTimeMinutes,
+        tankId: tank.id,
+        gasMix: tank.gasMix,
+        order: 1,
+      ),
+    ];
 
     state = state.copyWith(
       segments: segments,
@@ -507,8 +522,5 @@ final planIsValidProvider = Provider<bool>((ref) {
 /// Currently selected segment for editing.
 final selectedSegmentIdProvider = StateProvider<String?>((ref) => null);
 
-/// Currently selected tab index in planner page.
-final plannerTabIndexProvider = StateProvider<int>((ref) => 0);
-
 /// Whether the simple plan dialog is shown.
 final showSimplePlanDialogProvider = StateProvider<bool>((ref) => false);