fix(ical): fiabiliser le parsing Pronote 2026

Revue Codex validée. Corrections de parsing iCal, conservation du contexte des devoirs et fixtures anonymisées.

Co-authored-by: Codex <codex@antoineve.me>
Co-committed-by: Codex <codex@antoineve.me>

pronote_sync/sync/serialization.py

@@ -61,6 +61,10 @@ def lesson_to_vevent(lesson: Lesson) -> Event:
         parts.append(f"Professeur(s): {', '.join(lesson.teachers)}")
     if lesson.rooms:
         parts.append(f"Salle(s): {', '.join(lesson.rooms)}")
+    if lesson.group:
+        parts.append(f"Groupe: {lesson.group}")
+    if lesson.class_part:
+        parts.append(f"Partie(s) de classe: {lesson.class_part}")
     if lesson.content:
         parts.append(f"Contenu: {lesson.content}")
     event.add("description", "\n".join(parts))