refactor: remove bottom navigation bar (#665 #666 #667 #668) (#672)

* refactor(nav): remove bottom NavigationBar from Scaffold (#665)

* refactor(theme): remove BottomNavDisplayMode enum (#666)

* refactor(settings): remove nav bar customization page (#667)

* chore: clean up unused imports after bottom nav removal (#668)

* chore: remove dead bottom nav infrastructure after removal

- Remove SettingsNavBar NavKey (NavigationKeys.kt)
- Remove bottomNavItems field from ServerStoreState + migration code
- Remove _bottomNavItemsFlow, getBottomNavItems, setBottomNavItems from AuthManager
- Remove bottomNavItems handling from selfHealed() (ServerCollectionOps)
- Remove redundant bottomBar={} from Scaffold (Navigation.kt)
- Remove unused nav bar strings from values/strings.xml + values-ko/strings.xml
- Remove content_desc_move_up/down/remove_item strings
- Update SettingsViewModelTest.kt (drop stale getBottomNavItems mock)
- Update ServerStoreTest.kt (remove bottomNavItems assertions)

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Co-authored-by: M57 <Hy4ri@users.noreply.github.com>

app/src/main/java/com/m57/hermescontrol/NavigationKeys.kt

@@ -61,8 +61,6 @@ import kotlinx.serialization.Serializable
 
 @Serializable data object SettingsChat : NavKey
 
-@Serializable data object SettingsNavBar : NavKey
-
 @Serializable data object SettingsBehavior : NavKey
 
 @Serializable data object SettingsAbout : NavKey