Workstream C: extract player sleep-timer/autoplay and session commands into submodules

- commands/player/timers.rs: sleep-timer + autoplay commands (8).
- commands/player/session.rs: media session get/dismiss commands (2).
- Make create_media_item and get_player_status pub(super) so the submodules can
  reuse them. mod.rs shrinks from ~2720 to ~2229 lines; invoke_handler unchanged.

src-tauri/src/commands/player/session.rs

@@ -0,0 +1,43 @@
+//! Media session state commands.
+//!
+//! Read and dismiss the current media session (the Now Playing surface backing
+//! lockscreen/notification controls).
+
+use tauri::State;
+
+use super::{MediaSessionManagerWrapper, PlayerStateWrapper};
+use crate::player::PlayerStatusEvent;
+
+/// Get the current media session state
+#[tauri::command]
+pub async fn player_get_session(
+    session: State<'_, MediaSessionManagerWrapper>,
+) -> Result<crate::player::session::MediaSessionType, String> {
+    let manager = session.0.lock().map_err(|e| e.to_string())?;
+    Ok(manager.current().clone())
+}
+
+/// Dismiss the current media session (returns to Idle)
+#[tauri::command]
+pub async fn player_dismiss_session(
+    session: State<'_, MediaSessionManagerWrapper>,
+    player: State<'_, PlayerStateWrapper>,
+) -> Result<(), String> {
+    log::info!("[Session] Dismissing current media session");
+
+    // Dismiss the session
+    {
+        let mut manager = session.0.lock().map_err(|e| e.to_string())?;
+        manager.dismiss();
+    }
+
+    // Emit session changed event
+    if let Some(emitter) = player.0.lock().await.event_emitter() {
+        let manager = session.0.lock().map_err(|e| e.to_string())?;
+        emitter.emit(PlayerStatusEvent::SessionChanged {
+            session: manager.current().clone(),
+        });
+    }
+
+    Ok(())
+}