respect autoplay; add play_playlist() for manual start

DynamicSoundPlayerCore.ready() always called play() if a playlist had songs,
ignoring the inherited AudioStreamPlayer.autoplay property. Now early-returns
when autoplay is false. Adds play_playlist() (exposed on all three continuous
wrappers) so users with autoplay=false have a non-fade way to start playback.
fade_in() now uses the same _start_playback() helper.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

README.md

@@ -72,15 +72,16 @@ When the node enters the tree in the editor, `stream` is auto-assigned an `Audio
 
 | Method | Description |
 | --- | --- |
+| `play_playlist()` | Starts (or resumes) the playlist. Use this when `autoplay` is `false` and you want to start playback programmatically. |
 | `pause()` | Pauses playback. No-op if not playing or already paused. |
 | `resume()` | Resumes playback after a pause. |
 | `is_song_playing() -> bool` | True iff a song's layers are active and not paused. Distinct from `is_playing()`, which stays true between songs because the polyphonic playback session itself is still live. |
-| `fade_in(duration: float)` | Starts playback (if needed), unpauses, and ramps volume from silent to `volume_db` over `duration` seconds. |
+| `fade_in(duration: float)` | Starts playback (if needed), unpauses, and ramps volume from silent to `volume_db` over `duration` seconds. Works regardless of `autoplay`. |
 | `fade_out(duration: float)` | Ramps volume from current level to silent over `duration` seconds, then stops the polyphonic session. A subsequent `fade_in` reinitialises. |
 
 #### Behaviour
 
-- **Autoplay.** On `_ready`, plays the front song of the playlist.
+- **Autoplay.** On `_ready`, plays the front song of the playlist *only if `autoplay` is true* (the inherited `AudioStreamPlayer.autoplay` property; default `true`). Set `autoplay = false` to defer playback to a `play_playlist()` or `fade_in()` call.
 - **Advancement.** When a song's `Intensity1` length elapses, the player pops it from the queue and plays the next. With `Loop = true`, the popped song is re-appended to the back.
 - **Volume.** `volume_db` is honoured; the fade adjustment is layered on top internally, so manual volume changes during a fade still work correctly.
 - **Editor.** All scripts are `@tool`, but `_ready` and `_process` early-return in the editor so audio doesn't play in the inspector.

src/DynamicSoundPlayer.gd

@@ -45,6 +45,10 @@ func _ready() -> void:
 func _process(delta: float) -> void:
 	if _core: _core.process(delta);
 
+## Start (or resume) playlist playback. Useful when [code]autoplay[/code] is false.
+func play_playlist() -> void:
+	if _core: _core.play_playlist();
+
 ## Pause playback. Call [method resume] to continue.
 func pause() -> void:
 	if _core: _core.pause();

src/DynamicSoundPlayer2d.gd

@@ -44,6 +44,10 @@ func _ready() -> void:
 func _process(delta: float) -> void:
 	if _core: _core.process(delta);
 
+## Start (or resume) playlist playback. Useful when [code]autoplay[/code] is false.
+func play_playlist() -> void:
+	if _core: _core.play_playlist();
+
 ## Pause playback. Call [method resume] to continue.
 func pause() -> void:
 	if _core: _core.pause();

src/DynamicSoundPlayer3d.gd

@@ -44,6 +44,10 @@ func _ready() -> void:
 func _process(delta: float) -> void:
 	if _core: _core.process(delta);
 
+## Start (or resume) playlist playback. Useful when [code]autoplay[/code] is false.
+func play_playlist() -> void:
+	if _core: _core.play_playlist();
+
 ## Pause playback. Call [method resume] to continue.
 func pause() -> void:
 	if _core: _core.pause();

src/DynamicSoundPlayerCore.gd

@@ -31,11 +31,25 @@ func _init(player) -> void:
 func ready() -> void:
 	if Engine.is_editor_hint():
 		return;
+	if not _player.autoplay:
+		return;
+	_start_playback();
+
+## Starts (or resumes) playlist playback. Useful when [code]autoplay[/code] is false.
+func play_playlist() -> void:
+	if _paused:
+		resume();
+		return;
+	_start_playback();
+
+func _start_playback() -> void:
 	var playlist : DynamicSoundPlaylist = _player.Playlist;
 	if playlist == null or playlist.QueuedSongs.is_empty():
 		return;
+	if _playback == null:
 		_player.play();
 		_playback = _player.get_stream_playback();
+	if Ids.is_empty():
 		_play_song(playlist.QueuedSongs[0]);
 
 func process(delta: float) -> void:
@@ -88,14 +102,9 @@ func is_song_playing() -> bool:
 	return not Ids.is_empty() and not _paused;
 
 func fade_in(duration: float) -> void:
-	if _playback == null:
+	_start_playback();
-		_player.play();
-		_playback = _player.get_stream_playback();
 	if _paused:
 		resume();
-	var playlist : DynamicSoundPlaylist = _player.Playlist;
-	if Ids.is_empty() and playlist != null and not playlist.QueuedSongs.is_empty():
-		_play_song(playlist.QueuedSongs[0]);
 	_start_fade(_FADE_SILENT_DB, 0.0, duration, false);
 
 func fade_out(duration: float) -> void: