Fix Invalid ID3TimeStamp error when writing date tags

Strip non-timestamp characters (BOM, invisible chars) from date/year values
both when reading existing tags in metadata_resolver and when writing in
executor. Also harden the EasyID3 except block to not wipe existing tags
when adding a missing ID3 header, and add per-field try/except in MP3 tag
writing so one bad field doesn't abort the entire track.

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

executor.py

@@ -73,7 +73,10 @@ def write_tags(path: Path, proposal: TrackProposal, album_proposal: AlbumProposa
     if proposal.disc_number:
         tags_to_write["discnumber"] = str(proposal.disc_number)
     if album_proposal.date:
-        tags_to_write["date"] = album_proposal.date
+        # Strip everything except valid ID3 timestamp characters to prevent ID3TimeStamp errors
+        date_clean = re.sub(r"[^\d\-T:+Z]", "", str(album_proposal.date)).strip()
+        if date_clean:
+            tags_to_write["date"] = date_clean
     if album_proposal.genre:
         tags_to_write["genre"] = album_proposal.genre
     if album_proposal.label:
@@ -84,11 +87,22 @@ def write_tags(path: Path, proposal: TrackProposal, album_proposal: AlbumProposa
             try:
                 audio = EasyID3(str(path))
             except Exception:
-                audio = EasyID3()
-                audio.save(str(path))
+                # File has no ID3 header — add one without wiping audio data
+                from mutagen.id3 import ID3NoHeaderError
+                try:
+                    from mutagen.mp3 import MP3
+                    full = MP3(str(path))
+                    full.tags = None
+                    full.add_tags()
+                    full.save(str(path), v2_version=4)
+                except Exception:
+                    pass
                 audio = EasyID3(str(path))
             for k, v in tags_to_write.items():
-                audio[k] = [v]
+                try:
+                    audio[k] = [v]
+                except Exception as tag_err:
+                    print(f"  ⚠️ Tag-Feld '{k}' übersprungen ({path.name}): {tag_err}", file=sys.stderr)
             audio.save(v2_version=4)
             return True
 

metadata_resolver.py

@@ -337,8 +337,12 @@ def resolve(
         album = album or Counter(tag_albums).most_common(1)[0][0]
 
     # Tag year/genre/label
+    import re as _re
     for t in hints.tracks:
-        year = year or t.existing_tags.get("date") or t.existing_tags.get("year")
+        raw_year = t.existing_tags.get("date") or t.existing_tags.get("year")
+        if raw_year and not year:
+            # Strip invisible chars so ID3TimeStamp validation doesn't fail later
+            year = _re.sub(r"[^\d\-T:+Z]", "", str(raw_year)).strip()[:10] or None
         genre = genre or t.existing_tags.get("genre")
         label = label or t.existing_tags.get("label") or t.existing_tags.get("organization")