feat(events): reliable holiday skipping for recurrences + UI badge; clean logs

Backend: generate EventException on create/update when skip_holidays or recurrence changes; emit RecurrenceException (EXDATE) with exact occurrence start time (UTC)
API: return master events with RecurrenceRule + RecurrenceException
Frontend: map RecurrenceException → recurrenceException; ensure SkipHolidays instances never render on holidays; place TentTree icon (black) next to main event icon via template
Docs: update README and Copilot instructions for recurrence/holiday behavior
Cleanup: remove dataSource and debug console logs

server/wsgi.py

@@ -2,6 +2,7 @@
 from server.routes.eventmedia import eventmedia_bp
 from server.routes.files import files_bp
 from server.routes.events import events_bp
+from server.routes.event_exceptions import event_exceptions_bp
 from server.routes.conversions import conversions_bp
 from server.routes.holidays import holidays_bp
 from server.routes.academic_periods import academic_periods_bp
@@ -21,6 +22,7 @@ app = Flask(__name__)
 app.register_blueprint(clients_bp)
 app.register_blueprint(groups_bp)
 app.register_blueprint(events_bp)
+app.register_blueprint(event_exceptions_bp)
 app.register_blueprint(eventmedia_bp)
 app.register_blueprint(files_bp)
 app.register_blueprint(holidays_bp)