revert(android): top-nav Library icon back to Lucide.LibraryBig

Operator polled another user and reversed the earlier swap to
Material's LibraryMusic. Restore Lucide.LibraryBig and drop the
material-icons-extended Gradle dependency we added for the
intermediate icon, keeping the icon set Lucide-only.

android/app/build.gradle.kts

@@ -139,7 +139,6 @@ 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)