Add back stack for deep link navigation (#1756)

## Description
When testing the new deep link feature from this PR
[#1688](https://github.com/damontecres/Wholphin/pull/1688)
I noticed that the back button would close the app. As in, all routes
are cleared and only the playback is in the nav stack.

I figured a more desirable behavior would be to create a nav stack,
always starting with the home screen, then also inserting the media
item's details page, if available.

To achieve this, I made the return Target.destinations a list of
destinations, and updated the other two uses in IntentService.

Open to implementation tweaks, or scrap it if this isn't how it should
work, haha.

### Testing

Tested deep links, which produced the following nav stacks:
- Movie view
  - Home → Movie details
- Movie playback (with and without position)
  - Home → Movie details → Playback
- Series view
  - Home → Series details
- Season view
  - Home → Season details
- Episode view
  - Home → Episode details
- Episode playback (with and without position)
  - Home → Episode details → Playback
- Trailer/extras playback (no details page available)
  - Home → Playback
- TV channel view
  - Home → Playback
- TV channel playback
  - Home → Playback

## AI or LLM usage
AI was used to generate the initial code, debug and test, then manual
refactoring and cleanup was done.

---------

Co-authored-by: Damontecres <damontecres@gmail.com>

app/src/main/java/com/github/damontecres/wholphin/MainActivity.kt

@@ -449,7 +449,14 @@ class MainActivityViewModel
                                 val current = serverRepository.current.value
                                 if (current != null) {
                                     Timber.i("Received valid intent, switching to AppContent")
-                                    navigationManager.replace(result.destination)
+
+                                    if (result.addHomeToBackStack) {
+                                        navigationManager.reloadHome()
+                                    } else {
+                                        navigationManager.backStack.clear()
+                                    }
+                                    navigationManager.backStack.addAll(result.destinations)
+
                                     setupNavigationManager.navigateTo(
                                         SetupDestination.AppContent(current),
                                     )