feat(settings): move language to its own section with scalable dropdown picker (#906)

- New Language row in the main Settings list with current-language summary
- New SettingsLanguage drill-down page with an OutlinedButton + DropdownMenu
  picker (scales to any number of languages; same pattern as theme presets)
- Shared supportedLanguages()/languageLabel() helpers — adding a language
  is now one entry in one place
- Removed the 4-option segmented pill row from the Appearance page
- Added settings_sec_language string (en + zh)

Co-authored-by: M57 <hy4ri@users.noreply.github.com>

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

@@ -56,6 +56,7 @@ import com.m57.hermescontrol.ui.settings.SettingsAppearancePage
 import com.m57.hermescontrol.ui.settings.SettingsBehaviorPage
 import com.m57.hermescontrol.ui.settings.SettingsChatPage
 import com.m57.hermescontrol.ui.settings.SettingsConnectionPage
+import com.m57.hermescontrol.ui.settings.SettingsLanguagePage
 import com.m57.hermescontrol.ui.settings.SettingsViewModel
 import com.m57.hermescontrol.ui.toolsets.ToolsetDetailScreen
 import kotlinx.coroutines.launch
@@ -113,6 +114,12 @@ private fun appEntryProvider(
             viewModel = viewModel { SettingsViewModel() },
         )
     }
+    entry<SettingsLanguage> {
+        SettingsLanguagePage(
+            onBack = { NavigationController.goBack() },
+            viewModel = viewModel { SettingsViewModel() },
+        )
+    }
     entry<SettingsChat> {
         SettingsChatPage(
             onBack = { NavigationController.goBack() },