Lint-Fixes, process-Disc-Validierung und Forgejo-CI

- ruff: Import-Sortierung, unused imports, Zeilenlängen behoben
- cli.py: _check_disc_counts_or_exit() extrahiert; auch process-Befehl
  prüft jetzt Disc-Anzahlen vor dem Umbenennen
- .forgejo/workflows/ci.yml: ruff + pytest auf push/PR gegen main

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/test_cover.py

@@ -2,8 +2,6 @@
 
 from pathlib import Path
 
-import pytest
-
 from musiksammlung.cover import find_cover
 
 

tests/test_organizer.py

@@ -2,8 +2,6 @@
 
 from pathlib import Path
 
-import pytest
-
 from musiksammlung.models import Album, Disc, Track
 from musiksammlung.organizer import (
     _sanitize_filename,
@@ -122,7 +120,10 @@ class TestCheckDiscCounts:
             album="B",
             discs=[
                 Disc(disc_number=1, tracks=[Track(track_number=1, title="T1")]),
-                Disc(disc_number=2, tracks=[Track(track_number=1, title="T2"), Track(track_number=2, title="T3")]),
+                Disc(
+                    disc_number=2,
+                    tracks=[Track(track_number=1, title="T2"), Track(track_number=2, title="T3")],
+                ),
             ],
         )
         results = check_disc_counts(album, tmp_path)

tests/test_playlist.py

@@ -10,7 +10,9 @@ def _make_album(n_tracks: int = 2, n_discs: int = 1) -> Album:
     discs = [
         Disc(
             disc_number=d,
-            tracks=[Track(track_number=i, title=f"Disc{d} Song {i}") for i in range(1, n_tracks + 1)],
+            tracks=[
+                Track(track_number=i, title=f"Disc{d} Song {i}") for i in range(1, n_tracks + 1)
+            ],
         )
         for d in range(1, n_discs + 1)
     ]

tests/test_ripper.py

@@ -2,8 +2,6 @@
 
 from pathlib import Path
 
-import pytest
-
 from musiksammlung.config import AudioFormat
 from musiksammlung.ripper import (
     RipperConfig,