feat(ui): add bottom navigation with 4 tabs

app/src/main/java/com/radiola/MainActivity.kt

@@ -4,15 +4,47 @@ import android.os.Bundle
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material3.Scaffold
+import androidx.compose.ui.Modifier
+import androidx.navigation.compose.NavHost
+import androidx.navigation.compose.composable
+import androidx.navigation.compose.rememberNavController
+import com.radiola.ui.navigation.BottomNavBar
+import com.radiola.ui.navigation.NavDestinations
 import com.radiola.ui.theme.RadiolaTheme
+import dagger.hilt.android.AndroidEntryPoint
 
+@AndroidEntryPoint
 class MainActivity : ComponentActivity() {
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         enableEdgeToEdge()
         setContent {
             RadiolaTheme {
-                // TODO: Navigation will go here
+                val navController = rememberNavController()
+                Scaffold(
+                    bottomBar = { BottomNavBar(navController) }
+                ) { paddingValues ->
+                    NavHost(
+                        navController = navController,
+                        startDestination = NavDestinations.Stations.route,
+                        modifier = Modifier.padding(paddingValues)
+                    ) {
+                        composable(NavDestinations.Stations.route) {
+                            // TODO: StationsScreen
+                        }
+                        composable(NavDestinations.Favorites.route) {
+                            // TODO: FavoritesScreen
+                        }
+                        composable(NavDestinations.History.route) {
+                            // TODO: HistoryScreen
+                        }
+                        composable(NavDestinations.Settings.route) {
+                            // TODO: SettingsScreen
+                        }
+                    }
+                }
             }
         }
     }

app/src/main/java/com/radiola/ui/navigation/BottomNavBar.kt

@@ -0,0 +1,32 @@
+package com.radiola.ui.navigation
+
+import androidx.compose.material3.Icon
+import androidx.compose.material3.NavigationBar
+import androidx.compose.material3.NavigationBarItem
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.navigation.NavController
+import androidx.navigation.compose.currentBackStackEntryAsState
+
+@Composable
+fun BottomNavBar(navController: NavController) {
+    val currentRoute = navController.currentBackStackEntryAsState().value?.destination?.route
+    NavigationBar {
+        NavDestinations.items.forEach { destination ->
+            NavigationBarItem(
+                icon = { Icon(destination.icon, contentDescription = destination.labelRes) },
+                label = { Text(destination.labelRes) },
+                selected = currentRoute == destination.route,
+                onClick = {
+                    if (currentRoute != destination.route) {
+                        navController.navigate(destination.route) {
+                            popUpTo(navController.graph.startDestinationId) { saveState = true }
+                            launchSingleTop = true
+                            restoreState = true
+                        }
+                    }
+                }
+            )
+        }
+    }
+}

app/src/main/java/com/radiola/ui/navigation/NavDestinations.kt

@@ -0,0 +1,23 @@
+package com.radiola.ui.navigation
+
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.Favorite
+import androidx.compose.material.icons.filled.Home
+import androidx.compose.material.icons.filled.Settings
+import androidx.compose.material.icons.filled.History
+import androidx.compose.ui.graphics.vector.ImageVector
+
+sealed class NavDestinations(
+    val route: String,
+    val labelRes: String,
+    val icon: ImageVector
+) {
+    data object Stations : NavDestinations("stations", "Радио", Icons.Default.Home)
+    data object Favorites : NavDestinations("favorites", "Избранное", Icons.Default.Favorite)
+    data object History : NavDestinations("history", "История", Icons.Default.History)
+    data object Settings : NavDestinations("settings", "Настройки", Icons.Default.Settings)
+
+    companion object {
+        val items = listOf(Stations, Favorites, History, Settings)
+    }
+}