feat: add local reminders and owned calendar synchronization

mobile/lib/domain/app_snapshot.dart

@@ -18,6 +18,7 @@ class AppSnapshot {
     this.settings = const AppSettings(),
     List<Course> courses = const [],
     this.importMetadata,
+    this.calendarCleanupPending = false,
     Map<String, String> calendarEventIds = const {},
   }) : courses = List.unmodifiable(courses),
        calendarEventIds = Map.unmodifiable(calendarEventIds);
@@ -25,12 +26,14 @@ class AppSnapshot {
   final List<Course> courses;
   final ImportMetadata? importMetadata;
   final Map<String, String> calendarEventIds;
+  final bool calendarCleanupPending;
   AppSnapshot copyWith({
     AppSettings? settings,
     List<Course>? courses,
     ImportMetadata? importMetadata,
     Map<String, String>? calendarEventIds,
     bool clearMetadata = false,
+    bool? calendarCleanupPending,
   }) => AppSnapshot(
     settings: settings ?? this.settings,
     courses: courses ?? this.courses,
@@ -38,6 +41,8 @@ class AppSnapshot {
         ? null
         : importMetadata ?? this.importMetadata,
     calendarEventIds: calendarEventIds ?? this.calendarEventIds,
+    calendarCleanupPending:
+        calendarCleanupPending ?? this.calendarCleanupPending,
   );
   Map<String, dynamic> toJson() => {
     'schemaVersion': 1,
@@ -66,6 +71,7 @@ class AppSnapshot {
             'parserVersion': importMetadata!.parserVersion,
           },
     'calendarEventIds': calendarEventIds,
+    'calendarCleanupPending': calendarCleanupPending,
   };
   static AppSnapshot fromJson(Map<String, dynamic> json) {
     try {
@@ -93,6 +99,8 @@ class AppSnapshot {
             );
       final metadata = json['importMetadata'];
       return AppSnapshot(
+        calendarCleanupPending:
+            (json['calendarCleanupPending'] ?? false) as bool,
         courses: values,
         settings: AppSettings(
           semester: term,