Harden app for 24-7 offline-first operation

lib/data/local/models.dart

@@ -77,6 +77,10 @@ class AppSettings extends HiveObject {
   @HiveField(19)
   String? lastSyncDate;
 
+  // Last automatic sync attempt timestamp (ISO8601).
+  @HiveField(32)
+  String? lastAutoSyncAttemptDate;
+
   // Slideshow image paths (local)
   @HiveField(20)
   List<String> slideshowImages;
@@ -148,6 +152,7 @@ class AppSettings extends HiveObject {
     this.mainScreenDurationSec = 15,
     this.slideDurationSec = 10,
     this.lastSyncDate,
+    this.lastAutoSyncAttemptDate,
     this.slideshowImages = const [],
     this.textScaleIndex = 1,
     this.useUnsplashBackground = false,
@@ -183,6 +188,7 @@ class AppSettings extends HiveObject {
     int? mainScreenDurationSec,
     int? slideDurationSec,
     String? lastSyncDate,
+    String? lastAutoSyncAttemptDate,
     List<String>? slideshowImages,
     int? textScaleIndex,
     bool? useUnsplashBackground,
@@ -217,6 +223,8 @@ class AppSettings extends HiveObject {
       mainScreenDurationSec: mainScreenDurationSec ?? this.mainScreenDurationSec,
       slideDurationSec: slideDurationSec ?? this.slideDurationSec,
       lastSyncDate: lastSyncDate ?? this.lastSyncDate,
+      lastAutoSyncAttemptDate:
+          lastAutoSyncAttemptDate ?? this.lastAutoSyncAttemptDate,
       slideshowImages: slideshowImages ?? this.slideshowImages,
       textScaleIndex: textScaleIndex ?? this.textScaleIndex,
       useUnsplashBackground: useUnsplashBackground ?? this.useUnsplashBackground,
@@ -266,6 +274,7 @@ class AppSettingsAdapter extends TypeAdapter<AppSettings> {
       mainScreenDurationSec: fields[17] as int? ?? 15,
       slideDurationSec: fields[18] as int? ?? 10,
       lastSyncDate: fields[19] as String?,
+      lastAutoSyncAttemptDate: fields[32] as String?,
       slideshowImages: (fields[20] as List?)?.cast<String>() ?? const [],
       textScaleIndex: fields[21] as int? ?? 1,
       useUnsplashBackground: fields[22] as bool? ?? false,
@@ -284,7 +293,7 @@ class AppSettingsAdapter extends TypeAdapter<AppSettings> {
   @override
   void write(BinaryWriter writer, AppSettings obj) {
     writer
-      ..writeByte(32)
+      ..writeByte(33)
       ..writeByte(0)..write(obj.masjidName)
       ..writeByte(1)..write(obj.masjidAddress)
       ..writeByte(2)..write(obj.cityIdApi)
@@ -305,6 +314,7 @@ class AppSettingsAdapter extends TypeAdapter<AppSettings> {
       ..writeByte(17)..write(obj.mainScreenDurationSec)
       ..writeByte(18)..write(obj.slideDurationSec)
       ..writeByte(19)..write(obj.lastSyncDate)
+      ..writeByte(32)..write(obj.lastAutoSyncAttemptDate)
       ..writeByte(20)..write(obj.slideshowImages)
       ..writeByte(21)..write(obj.textScaleIndex)
       ..writeByte(22)..write(obj.useUnsplashBackground)