🐛 | Code quality fixes

- config.py: move 'import shutil' to module level
- player.py: unify type hints, narrow except, add debug log
- discord_rpc.py: replace broad except Exception with specific types
- gui.py: remove unused import; replace lambda closures with method refs; fix closure scope bug; extract _populate_list_page() to remove duplicate code; add public accessors; make flush_volume public; add AudioVisualizer.reset_activity()
- tests: replace unused _f variable with Path.touch()

tests/test_player_helpers.py

@@ -4,6 +4,7 @@ import os
 import struct
 import math
 import tempfile
+from pathlib import Path
 
 import pytest
 
@@ -239,8 +240,9 @@ class TestStaleFiles:
         td = tempfile.mkdtemp(prefix="tunetti_test_")
         monkeypatch.setattr("player._TUNETTI_TMP", td)
 
-        with open(os.path.join(td, "vid123.mp3"), "w") as _f:
-            pass  # empty; _f unused intentionally
+        # Create an empty file to verify it's excluded
+        empty_path = os.path.join(td, "vid123.mp3")
+        Path(empty_path).touch()
 
         result = _stale_files("vid123")
         assert result == []