fix(android): MainAppBarActions sources isAdmin internally

The isAdmin parameter on MainAppBarActions defaulted to false and no
call site passed it, so the Admin overflow item never appeared for
actual admins — leaving the admin section unreachable from normal UI.

Move the lookup into a tiny AppBarActionsViewModel that reads
AuthController.currentUser, and drop the parameter from the public
signature so future call sites can't recreate the dead-param hazard.

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

android/app/src/main/java/com/fabledsword/minstrel/shared/widgets/AppBarActionsViewModel.kt

@@ -0,0 +1,33 @@
+package com.fabledsword.minstrel.shared.widgets
+
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import com.fabledsword.minstrel.auth.AuthController
+import dagger.hilt.android.lifecycle.HiltViewModel
+import kotlinx.coroutines.flow.SharingStarted
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.map
+import kotlinx.coroutines.flow.stateIn
+import javax.inject.Inject
+
+private const val SHARE_STOP_TIMEOUT_MS = 5_000L
+
+/**
+ * Backs [MainAppBarActions] with the current user's admin flag so the
+ * overflow "Admin" item appears for every admin without each shell
+ * screen having to plumb the value through. Sourced from
+ * [AuthController.currentUser] so it stays live across sign-in,
+ * sign-out, and role changes pushed via rehydration.
+ */
+@HiltViewModel
+class AppBarActionsViewModel @Inject constructor(
+    authController: AuthController,
+) : ViewModel() {
+    val isAdmin: StateFlow<Boolean> = authController.currentUser
+        .map { it?.isAdmin == true }
+        .stateIn(
+            scope = viewModelScope,
+            started = SharingStarted.WhileSubscribed(SHARE_STOP_TIMEOUT_MS),
+            initialValue = false,
+        )
+}

android/app/src/main/java/com/fabledsword/minstrel/shared/widgets/MainAppBarActions.kt

@@ -11,6 +11,8 @@ import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
+import androidx.hilt.navigation.compose.hiltViewModel
+import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.navigation.NavHostController
 import com.composables.icons.lucide.House
 import com.composables.icons.lucide.LibraryBig
@@ -33,7 +35,9 @@ import com.fabledsword.minstrel.nav.Settings as SettingsRoute
  *   [Home] [Library] [Search] [ ⋮ Playlists / Discover / Settings / Admin ]
  *
  * The icon for the screen the user is currently on is suppressed so
- * the action set looks contextual.
+ * the action set looks contextual. The "Admin" overflow item is
+ * sourced internally from [AppBarActionsViewModel] so admins see it
+ * everywhere without each call site having to plumb the flag.
  *
  * `currentRouteName` is a soft string match against the destination
  * route name (route classes serialize to their FQN by default in
@@ -43,8 +47,9 @@ import com.fabledsword.minstrel.nav.Settings as SettingsRoute
 fun MainAppBarActions(
     navController: NavHostController,
     currentRouteName: String?,
-    isAdmin: Boolean = false,
+    viewModel: AppBarActionsViewModel = hiltViewModel(),
 ) {
+    val isAdmin by viewModel.isAdmin.collectAsStateWithLifecycle()
     Row {
         if (currentRouteName != Home::class.qualifiedName) {
             IconButton(onClick = { navController.navigate(Home) }) {