fix(android): rename state_ → internal (detekt VariableNaming)

Trailing-underscore name tripped detekt's `(_)?[a-z][A-Za-z0-9]*`
pattern. `internal` matches the naming convention every other VM
in the codebase uses for the private MutableStateFlow shadowed by
a public StateFlow.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

android/app/src/main/java/com/fabledsword/minstrel/settings/ui/SettingsViewModel.kt

@@ -27,8 +27,8 @@ class SettingsViewModel @Inject constructor(
 ) : ViewModel() {
 
     private val transient = MutableStateFlow(TransientState())
-    private val state_: MutableStateFlow<SettingsState> = MutableStateFlow(SettingsState())
-    val state: StateFlow<SettingsState> = state_.asStateFlow()
+    private val internal: MutableStateFlow<SettingsState> = MutableStateFlow(SettingsState())
+    val state: StateFlow<SettingsState> = internal.asStateFlow()
 
     init {
         // Compose the user-visible state from the auth observables
@@ -48,7 +48,7 @@ class SettingsViewModel @Inject constructor(
                     isSigningOut = t.isSigningOut,
                     signedOut = t.signedOut,
                 )
-            }.collect { state_.value = it }
+            }.collect { internal.value = it }
         }
     }