fix: normalizar sync de google sheets para todos los dias, reparar 500 en ciclos lectivos, selector de ciclo lectivo en comisiones y opciones --keep-db --keep-users en install.sh

backend/app/models/subject.py

@@ -61,6 +61,10 @@ class Commission(db.Model):
     grades_closed_by = db.Column(db.Integer, db.ForeignKey('users.id', ondelete='SET NULL'), nullable=True)
     acta_number = db.Column(db.String(50), nullable=True)
 
+    # Vinculación con Ciclo Lectivo / Período Académico
+    academic_term_id = db.Column(db.Integer, db.ForeignKey('academic_terms.id', ondelete='SET NULL'), nullable=True)
+    academic_term = db.relationship('AcademicTerm', foreign_keys=[academic_term_id])
+
     created_at = db.Column(db.DateTime, default=datetime.utcnow)
     updated_at = db.Column(db.DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
     
@@ -138,6 +142,7 @@ class Commission(db.Model):
             'grades_closed_by': self.grades_closed_by,
             'closed_by_name': self.closed_by_user.name if self.closed_by_user else None,
             'acta_number': self.acta_number,
+            'academic_term_id': self.academic_term_id,
             'created_at': self.created_at.isoformat() if self.created_at else None,
             'updated_at': self.updated_at.isoformat() if self.updated_at else None,
             'full_code': self.get_full_code(),