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/build.gradle.kts

@@ -139,6 +139,7 @@ dependencies {
     implementation(libs.compose.ui)
     implementation(libs.compose.ui.graphics)
     implementation(libs.compose.material3)
+    implementation(libs.compose.material.icons.extended)
     implementation(libs.compose.ui.text.google.fonts)
     debugImplementation(libs.compose.ui.tooling)
     implementation(libs.compose.ui.tooling.preview)