feat(android): use Material Outlined LibraryMusic for top-nav Library

Lucide has no music-library glyph — Library / LibraryBig /
SquareLibrary all read as a generic books-on-shelf icon without
a label. Operator picked Material's LibraryMusic (the canonical
"books + music note" symbol used by every major music app) as
the recognizable alternative.

Use the Outlined variant: filled icons would clash with the
neighbouring stroked Lucide icons (House, Search, EllipsisVertical),
but Outlined's stroke style matches Lucide closely enough that
the mix is subtle.

Adds the compose-material-icons-extended dependency (version
pinned by compose-bom). R8 strips unused icons in release builds
so the APK cost is just the ones we actually reference.

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

@@ -11,12 +11,13 @@ import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.outlined.LibraryMusic
 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.Lucide
-import com.composables.icons.lucide.SquareLibrary
 import com.composables.icons.lucide.EllipsisVertical
 import com.composables.icons.lucide.Search as SearchIcon
 import com.fabledsword.minstrel.nav.Admin
@@ -58,7 +59,14 @@ fun MainAppBarActions(
         }
         if (currentRouteName != Library::class.qualifiedName) {
             IconButton(onClick = { navController.navigate(Library) }) {
-                Icon(Lucide.SquareLibrary, contentDescription = "Library")
+                // Intentional cross-family icon — Lucide has no
+                // equivalent "library + music" glyph and the literal
+                // library icons (Library / LibraryBig / SquareLibrary)
+                // don't read as "music collection" without a label.
+                // Material's Outlined LibraryMusic is the canonical
+                // music-library symbol; the outlined variant matches
+                // Lucide's stroke style closely enough to blend.
+                Icon(Icons.Outlined.LibraryMusic, contentDescription = "Library")
             }
         }
         if (currentRouteName != SearchRoute::class.qualifiedName) {