feat(android): gate Focus tab behind focus_mode_enabled feature flag

android/app/src/main/java/com/chronomind/app/ui/navigation/NavHost.kt

@@ -22,6 +22,9 @@ import com.chronomind.app.ui.screens.HistoryScreen
 import com.chronomind.app.ui.screens.SettingsScreen
 import com.chronomind.app.ui.screens.TimelineScreen
 import com.chronomind.app.ui.theme.CMColors
+import com.bytelyst.platform.BLFeatureFlagClient
+import dagger.hilt.android.EntryPointAccessors
+import androidx.compose.ui.platform.LocalContext
 
 sealed class Screen(val route: String, val label: String, val icon: ImageVector) {
     data object Timeline : Screen("timeline", "Timeline", Icons.Filled.Schedule)
@@ -32,9 +35,24 @@ sealed class Screen(val route: String, val label: String, val icon: ImageVector)
 
 val bottomNavItems = listOf(Screen.Timeline, Screen.Focus, Screen.History, Screen.Settings)
 
+@dagger.hilt.InstallIn(dagger.hilt.components.SingletonComponent::class)
+@dagger.hilt.EntryPoint
+interface NavFlagEntryPoint {
+    fun featureFlagClient(): BLFeatureFlagClient
+}
+
 @Composable
 fun ChronoMindNavHost() {
     val navController = rememberNavController()
+    val context = LocalContext.current
+    val entryPoint = EntryPointAccessors.fromApplication(context, NavFlagEntryPoint::class.java)
+    val flagClient = entryPoint.featureFlagClient()
+    val visibleNavItems = bottomNavItems.filter { screen ->
+        when (screen) {
+            is Screen.Focus -> flagClient.isEnabled("focus_mode_enabled")
+            else -> true
+        }
+    }
 
     Scaffold(
         containerColor = CMColors.bg,
@@ -46,7 +64,7 @@ fun ChronoMindNavHost() {
                 val navBackStackEntry by navController.currentBackStackEntryAsState()
                 val currentDestination = navBackStackEntry?.destination
 
-                bottomNavItems.forEach { screen ->
+                visibleNavItems.forEach { screen ->
                     val selected = currentDestination?.hierarchy?.any { it.route == screen.route } == true
                     NavigationBarItem(
                         icon = { Icon(screen.icon, contentDescription = screen.label) },