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.

media.py

@@ -3,7 +3,6 @@
 from __future__ import annotations
 
 import json
-from pathlib import Path
 
 from mtsmusic import CONFIG_DIR
 
@@ -12,7 +11,8 @@ HISTORY_LIMIT = 100
 
 
 def track_artist(track: dict) -> str:
-    return ", ".join(a.get("name", "?") for a in track.get("artists") or []) or "?"
+    return ", ".join(a.get("name", "?")
+                     for a in track.get("artists") or []) or "?"
 
 
 def track_album(track: dict) -> str:
@@ -58,7 +58,9 @@ def record_history(track: dict) -> list[dict]:
     track_id = str(track.get("id") or "")
     if not track_id:
         return load_history()
-    history = [item for item in load_history() if str(item.get("id")) != track_id]
+    history = [
+        item for item in load_history() if str(
+            item.get("id")) != track_id]
     history.insert(0, track)
     history = history[:HISTORY_LIMIT]
     try: