feat: 实现日历提醒 in-app fallback 机制及通知服务重构

apps/lib/features/home/ui/controllers/home_keyboard_inset_calculator.dart

@@ -0,0 +1,19 @@
+import '../../../../core/theme/design_tokens.dart';
+
+class HomeKeyboardInsetCalculator {
+  static double compute({
+    required double rawViewInsetBottom,
+    required double bottomViewPadding,
+  }) {
+    if (rawViewInsetBottom <= AppSpacing.xs) {
+      return 0;
+    }
+
+    final adjustedInset = rawViewInsetBottom - bottomViewPadding;
+    if (adjustedInset <= AppSpacing.xs) {
+      return 0;
+    }
+
+    return adjustedInset;
+  }
+}

apps/lib/features/home/ui/screens/home_screen.dart

@@ -14,6 +14,7 @@ import '../../../chat/presentation/bloc/agent_stage.dart';
 import '../../../chat/presentation/bloc/chat_bloc.dart';
 import '../../../messages/data/inbox_api.dart';
 import '../../data/voice_recorder.dart';
+import '../controllers/home_keyboard_inset_calculator.dart';
 import '../controllers/home_message_viewport_controller.dart';
 import '../controllers/home_viewport_coordinator.dart';
 import '../../../../shared/widgets/app_pull_refresh_feedback.dart';
@@ -100,7 +101,6 @@ class _HomeScreenState extends State<HomeScreen>
   double? _historyViewportMaxExtent;
   final GlobalKey<HomeInputHostState> _inputHostKey =
       GlobalKey<HomeInputHostState>();
-  double _stableKeyboardInset = 0;
 
   @override
   void initState() {
@@ -541,16 +541,10 @@ class _HomeScreenState extends State<HomeScreen>
 
   double _effectiveKeyboardInset(BuildContext context) {
     final mediaQuery = MediaQuery.of(context);
-    final rawInset = mediaQuery.viewInsets.bottom;
-    if (rawInset <= AppSpacing.xs) {
-      _stableKeyboardInset = 0;
-      return 0;
-    }
-    // Only update stable if new value is larger (never decrease on jitter down)
-    if (rawInset > _stableKeyboardInset) {
-      _stableKeyboardInset = rawInset;
-    }
-    return _stableKeyboardInset;
+    return HomeKeyboardInsetCalculator.compute(
+      rawViewInsetBottom: mediaQuery.viewInsets.bottom,
+      bottomViewPadding: mediaQuery.viewPadding.bottom,
+    );
   }
 
   void _dismissKeyboard() {