feat: gestion de materias por rol - Bedelia, Docente y Alumno

- Nuevo modelo StudentEnrollment (tabla student_enrollments)
  con inscripcion unica por alumno/comision, estado y notas

- Migracion automatica en init_db.py (CREATE TABLE IF NOT EXISTS)

- Rutas /admin/commissions/ para Bedelia y Admin:
  listado con filtros, detalle, asignar docente,
  inscribir/dar de baja alumnos, cambiar estado

- Blueprint my_subjects_bp en /mis-materias:
  Docente ve solo sus comisiones asignadas
  Alumno ve solo sus inscripciones activas
  Admin/Bedelia ven todo

- Templates: admin/commissions/list.html, detail.html
            my_subjects/list.html, detail.html

- Navbar actualizado por rol:
  Docente y Alumno: 'Mis Materias'
  Bedelia y Admin: 'Gestion de Comisiones'

app/__init__.py

@@ -31,7 +31,7 @@ def create_app(config_class=Config):
 # Import models to ensure they are registered
     from app.models import user
     # Register blueprints
-    from app.routes import auth_bp, classrooms_bp, buildings_bp, main_bp, schedule_bp, genetic_bp, genetic_web_bp, admin_bp
+    from app.routes import auth_bp, classrooms_bp, buildings_bp, main_bp, schedule_bp, genetic_bp, genetic_web_bp, admin_bp, my_subjects_bp
     from app.routes.api import api_auth_bp, api_classrooms_bp, api_reservations_bp, api_optimizer_bp
     from app.security import SecurityFilterChain
     
@@ -43,6 +43,7 @@ def create_app(config_class=Config):
     app.register_blueprint(genetic_bp)
     app.register_blueprint(genetic_web_bp)
     app.register_blueprint(admin_bp)
+    app.register_blueprint(my_subjects_bp)
 
     # Register REST API (v1) Blueprints with Stateless JWT support
     app.register_blueprint(api_auth_bp)