style: format all code to PEP8 (flake8 clean)

Reformat every module with autopep8 and hand-tune the remaining long
lines so that `flake8` passes with default settings (max line length
79). No behavior changes: long f-strings, messages, QSS/Textual CSS
rules and argument lists are only wrapped or split, an unused import
and an unused local are dropped, and dbus-next D-Bus signature
annotations carry targeted `# noqa` comments.

settings.py

@@ -42,7 +42,8 @@ def _coerce(key: str, value: Any) -> Any:
     if key in ("autoplay", "wave_from_history"):
         if isinstance(value, bool):
             return value
-        return str(value).strip().lower() in ("1", "true", "yes", "on", "да", "вкл")
+        return str(value).strip().lower() in (
+            "1", "true", "yes", "on", "да", "вкл")
     if key == "start_queue":
         text = str(value)
         return text if text in START_QUEUES else DEFAULTS[key]