Create or update an availability schedule for a Cal.com user via API v2

Documented steps

1. Create: POST https://api.cal.com/v2/schedules — Update: PATCH https://api.cal.com/v2/schedules/{scheduleId}
2. Headers: cal-api-version: 2024-06-11, Authorization: Bearer <api_key or managed-user access token>, Content-Type: application/json
3. POST body: {"name": "...", "timeZone": "<IANA id, e.g. Europe/Rome>", "isDefault": true|false, "availability": [{"days": ["Monday", ...], "startTime": "09:00", "endTime": "17:00"}]}
4. Optional date-specific overrides: {"overrides": [{"date": "YYYY-MM-DD", "startTime": "HH:MM", "endTime": "HH:MM"}]}
5. Response: {status: 'success', data: {id, name, timeZone, isDefault, availability, ...}} — event types pick up the default schedule automatically
6. Docs: https://cal.com/docs/api-reference/v2/schedules/create-a-schedule and https://cal.com/docs/api-reference/v2/schedules/update-a-schedule