Export all account data (GDPR Art. 15 + 20 portability)

Returns a JSON dump of every row this org owns: agents, calendars, events (with decrypted titles + descriptions), iCal subscriptions (with decrypted URL), webhook subscriptions (with decrypted secret), availability rules, scheduling proposals + slots + responses, API key prefixes, ToS acceptance history, and usage/quota counters. Internal infrastructure data (incident_records, scheduling internals, password/OTP/key hashes, claim tokens) is excluded. JWT-authenticated (console session cookie or Bearer token). Rate-limited to 10 exports/hour/org. Response includes Cache-Control: no-store and Content-Disposition: attachment so the browser triggers a download.