feat: Add auto-sync, fix partner linking UI, update sharing settings

- Add 10-second periodic auto-sync to CycleEntriesNotifier
- Fix husband_devotional_screen: use partnerId for isConnected check, navigate to SharingSettingsScreen instead of legacy mock dialog
- Remove obsolete _showConnectDialog method and mock data import
- Update husband_settings_screen: show 'Partner Settings' with linked partner name when connected
- Add SharingSettingsScreen: Pad Supplies toggle (disabled when pad tracking off), Intimacy always enabled
- Add CORS OPTIONS handler to backend server
- Add _ensureServerRegistration for reliable partner linking
- Add copy button to Invite Partner dialog
- Dynamic base URL for web (uses window.location.hostname)

lib/models/user_profile.dart

@@ -313,6 +313,9 @@ class UserProfile extends HiveObject {
   @HiveField(56, defaultValue: false)
   bool useExampleData;
 
+  @HiveField(57)
+  String? partnerId; // ID of the partner to sync with
+
   UserProfile({
     required this.id,
     required this.name,
@@ -370,6 +373,7 @@ class UserProfile extends HiveObject {
     this.husbandThemeMode = AppThemeMode.system,
     this.husbandAccentColor = '0xFF1A3A5C',
     this.useExampleData = false,
+    this.partnerId,
   });
 
   /// Check if user is married
@@ -452,6 +456,7 @@ class UserProfile extends HiveObject {
     AppThemeMode? husbandThemeMode,
     String? husbandAccentColor,
     bool? useExampleData,
+    String? partnerId,
   }) {
     return UserProfile(
       id: id ?? this.id,
@@ -513,6 +518,7 @@ class UserProfile extends HiveObject {
       husbandThemeMode: husbandThemeMode ?? this.husbandThemeMode,
       husbandAccentColor: husbandAccentColor ?? this.husbandAccentColor,
       useExampleData: useExampleData ?? this.useExampleData,
+      partnerId: partnerId ?? this.partnerId,
     );
   }
 }