🐛 | 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()

config.py

@@ -1,6 +1,7 @@
 """Tunetti configuration — stored at ~/.config/tunetti/config.json ."""
 
 import json
+import shutil
 from pathlib import Path
 
 # ── Config file location (XDG compliant) ──────────────────────────────────
@@ -42,7 +43,6 @@ def _migrate_legacy() -> None:
         if old_db_path.parent == Path(__file__).parent and old_db_path.exists():
             new_db_path = CONFIG_DIR / "music_history.db"
             if not new_db_path.exists():
-                import shutil
                 shutil.copy2(str(old_db_path), str(new_db_path))
             old["db_path"] = str(new_db_path)