fix(daemon): Replace unwrap with safe Option handling in audio_player (#125)

The `play` method in `src/types/audio_player.rs` previously used `.unwrap()`
directly on `self.stream_handle.as_ref()`. This posed a security/stability risk
where if `stream_handle` was uninitialized or became `None` unexpectedly
despite the prior `ensure_stream()` call, it would cause the thread to panic
and potentially crash the application.

This commit replaces the `.unwrap()` call with `.ok_or_else` to safely handle
the `None` case, returning an `anyhow` error instead of panicking, adhering to
the project's no-panic policy.

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

src/types/audio_player.rs

@@ -349,7 +349,11 @@ impl AudioPlayer {
 
                 let duration = source.total_duration().map(|d| d.as_secs_f32());
 
-                let mixer = self.stream_handle.as_ref().unwrap().mixer();
+                let mixer = self
+                    .stream_handle
+                    .as_ref()
+                    .ok_or_else(|| anyhow::anyhow!("stream_handle is unexpectedly missing"))?
+                    .mixer();
                 let sink = Player::connect_new(mixer);
                 sink.set_volume(self.volume); // Default volume is 1.0 * master
                 sink.append(source);