Add new drawable resources for icons and themes

- Created `archive_filled.xml` for filled archive icon.
- Added `bookmark_outlined.xml` for outlined bookmark icon.
- Introduced `day_theme_filled.xml` for day theme icon.
- Added `folder_outlined.xml` for outlined folder icon.
- Created `gear_outlined.xml` for outlined gear icon.
- Introduced `night_mode.xml` for night mode icon.

app/src/main/java/com/rosetta/messenger/data/PreferencesManager.kt

@@ -9,9 +9,13 @@ import androidx.datastore.preferences.core.intPreferencesKey
 import androidx.datastore.preferences.core.stringPreferencesKey
 import androidx.datastore.preferences.core.stringSetPreferencesKey
 import androidx.datastore.preferences.preferencesDataStore
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.launch
 
 private val Context.dataStore: DataStore<Preferences> by
         preferencesDataStore(name = "rosetta_preferences")
@@ -75,13 +79,23 @@ class PreferencesManager(private val context: Context) {
         context.dataStore.edit { preferences -> preferences[IS_DARK_THEME] = value }
     }
 
-    val themeMode: Flow<String> =
-            context.dataStore.data.map { preferences ->
-                preferences[THEME_MODE] ?: "dark" // Default to dark theme
-            }
+    // In-memory cache for instant theme switching (no DataStore disk I/O delay)
+    private val _themeMode = MutableStateFlow("dark")
+    private val themeModeInitScope = CoroutineScope(Dispatchers.IO)
+
+    init {
+        // Load persisted value on startup
+        themeModeInitScope.launch {
+            val persisted = context.dataStore.data.first()[THEME_MODE] ?: "dark"
+            _themeMode.value = persisted
+        }
+    }
+
+    val themeMode: Flow<String> = _themeMode
 
     suspend fun setThemeMode(value: String) {
-        context.dataStore.edit { preferences -> preferences[THEME_MODE] = value }
+        _themeMode.value = value // Instant in-memory update
+        context.dataStore.edit { preferences -> preferences[THEME_MODE] = value } // Persist
     }
 
     // ═════════════════════════════════════════════════════════════