feat: editor playback + temp cleanup on close + docs (v1.6)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_ui_structure.py

@@ -1,3 +1,4 @@
+import os
 import pytest
 
 # Redirect QSettings to a throwaway dir BEFORE any MainWindow is constructed, so
@@ -729,3 +730,22 @@ def test_editor_undo_redo(win, tmp_path, monkeypatch):
     dlg._on_redo(); assert dlg._ver_idx == 1
     dlg._on_redo(); assert dlg._ver_idx == 2
     dlg._on_redo(); assert dlg._ver_idx == 2     # clamped at top
+
+
+def test_editor_play_stop_safe(win, tmp_path):
+    import main as m
+    src = tmp_path / "v0.wav"; src.write_bytes(b"")
+    dlg = m.AudioEditorDialog(str(src), parent=win)
+    dlg._stop_play()                      # no proc -> safe no-op
+    assert dlg._btn_play.text() == "▶ Play"
+
+
+def test_editor_close_cleans_temps(win, tmp_path):
+    import main as m
+    src = tmp_path / "v0.wav"; src.write_bytes(b"")
+    t1 = tmp_path / "t1.wav"; t1.write_bytes(b"x")
+    dlg = m.AudioEditorDialog(str(src), parent=win)
+    dlg._temps.add(str(t1))
+    dlg.close()
+    assert not t1.exists()
+    assert os.path.exists(str(src))       # _versions[0] (entry temp) is NOT swept by the editor