Refactor: Extract RootScreen from MainActivity and fix reply message user

This commit refactors the UI composition logic by extracting it from `MainActivity` into a new, dedicated `RootScreen` composable. This improves the separation of concerns and simplifies `MainActivity`.

Additionally, a bug has been fixed where a replied-to message would incorrectly display the author of the parent message instead of its own author.

Key changes:
- Moved theme setup, permission handling, Long-Poll/Online service management, and navigation graph hosting into the new `RootScreen.kt`.
- `MainActivity` is now significantly simplified, delegating its UI composition to `RootScreen`.
- Corrected the user and group assignment for `replyMessage` in `MessagesRepositoryImpl` to ensure the correct author is displayed.
- Introduced `OnlineFriendsViewModel` to the `FriendsRoute` to separate the logic for online friends.
- Replaced `List` with a custom `ImmutableList` for `photoViewerInfo` state to improve Compose stability.

feature/photoviewer/src/main/kotlin/dev/meloda/fast/photoviewer/presentation/PhotoViewScreen.kt

@@ -1,6 +1,5 @@
 package dev.meloda.fast.photoviewer.presentation
 
-import android.content.Intent
 import android.widget.Toast
 import androidx.compose.animation.AnimatedVisibility
 import androidx.compose.animation.core.Animatable
@@ -59,9 +58,9 @@ import dev.meloda.fast.photoviewer.model.PhotoViewScreenState
 import dev.meloda.fast.ui.R
 import dev.meloda.fast.ui.components.FullScreenDialog
 import dev.meloda.fast.ui.components.Loader
+import dev.meloda.fast.ui.util.ImmutableList
 import dev.meloda.fast.ui.util.getImage
 import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.flow.distinctUntilChanged
 import kotlinx.coroutines.launch
 import org.koin.androidx.compose.koinViewModel
 import java.net.URLEncoder
@@ -69,7 +68,7 @@ import kotlin.math.abs
 
 @Composable
 fun PhotoViewDialog(
-    photoViewerInfo: Pair<List<String>, Int?>?,
+    photoViewerInfo: Pair<ImmutableList<String>, Int?>?,
     modifier: Modifier = Modifier,
     onDismiss: () -> Unit
 ) {
@@ -85,7 +84,7 @@ fun PhotoViewDialog(
                     arguments = PhotoViewArguments(
                         imageUrls = photoViewerInfo.first.map {
                             URLEncoder.encode(it, "utf-8")
-                        },
+                        }.toList(),
                         selectedIndex = photoViewerInfo.second
                     ),
                     applicationContext = applicationContext