iOS 1.0.1: mini player, Now Playing spacing, play spinner fix

- Mini player floats as a solid card and every screen leaves room for it,
  so it no longer covers the bottom of lists
- More space between title and scrubber; panel switches animate
- Play button no longer spins forever after changing tracks: the engine
  now always reports buffering on load
- Springier button presses and play/pause symbol transitions

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

ios/Stemify/UI/RootView.swift

@@ -11,11 +11,14 @@ struct RootView: View {
         TabView(selection: Binding(get: { ui.tab }, set: { ui.selectTab($0) })) {
             ForEach(Tab.allCases, id: \.self) { t in
                 NavigationStack(path: ui.path(t)) {
-                    root(t).navigationDestination(for: Route.self) { destination($0) }
+                    root(t).miniPlayerRoom()
+                        .navigationDestination(for: Route.self) { destination($0).miniPlayerRoom() }
                 }
-                .safeAreaInset(edge: .bottom, spacing: 0) {
-                    if g.playback.current != nil { MiniPlayer() }
+                // Floats over the screens; each screen leaves room for it so nothing ends up underneath.
+                .overlay(alignment: .bottom) {
+                    if g.playback.current != nil { MiniPlayer().transition(.move(edge: .bottom).combined(with: .opacity)) }
                 }
+                .animation(.spring(duration: 0.35), value: g.playback.current != nil)
                 .tabItem { Label(t.rawValue, systemImage: t.icon) }
                 .tag(t)
             }
@@ -68,3 +71,16 @@ struct RootView: View {
         }
     }
 }
+
+private struct MiniPlayerRoom: ViewModifier {
+    private var g: AppGraph { .shared }
+    func body(content: Content) -> some View {
+        content.safeAreaInset(edge: .bottom, spacing: 0) {
+            if g.playback.current != nil { Color.clear.frame(height: 66) }
+        }
+    }
+}
+
+private extension View {
+    func miniPlayerRoom() -> some View { modifier(MiniPlayerRoom()) }
+}