Add public/private calendars, full iCal support, and iCal URL import

- Public/private: toggle is_public via PUT /calendars/{id}; generate/clear
  public_token and return ical_url when public
- Public feed: GET /cal/{token}/feed.ics (no auth) for subscription in
  Google/Apple/Outlook calendars
- Full iCal export: use golang-ical; VALARM, ATTENDEE, all-day (VALUE=DATE),
  RRULE, DTSTAMP, CREATED, LAST-MODIFIED
- Full iCal import: parse TZID, VALUE=DATE, VALARM, ATTENDEE, RRULE
- Import from URL: POST /calendars/import-url with calendar_id + url
- Migration: unique index on public_token, calendar_subscriptions table
- Config: BASE_URL for ical_url; Calendar model + API: ical_url field
- Docs: OpenAPI, llms.txt, README, SKILL.md, about/overview

Made-with: Cursor

README.md

@@ -9,7 +9,9 @@ A production-grade REST API for calendar management, event scheduling, contacts,
 - **Contacts** - Personal contact management with search
 - **Availability** - Query busy/free time across calendars
 - **Booking Links** - Public scheduling pages with configurable working hours, duration, and buffer time
-- **ICS Import/Export** - Standard iCalendar format compatibility
+- **ICS Import/Export** - Full RFC 5545 iCalendar support with VALARM, ATTENDEE, TZID, all-day events
+- **Public iCal Feeds** - Make calendars public and subscribe via iCal URL in any calendar app
+- **iCal URL Import** - Import events from any external iCal feed URL
 - **Dual Auth** - JWT tokens for interactive use, scoped API keys for agents and automation
 - **Background Jobs** - Reminder notifications via Redis + Asynq (optional)
 
@@ -214,6 +216,8 @@ X-API-Key: <token>
 |--------|----------|-------|-------------|
 | GET | `/calendars/{id}/export.ics` | calendars:read | Export as ICS |
 | POST | `/calendars/import` | calendars:write | Import ICS file |
+| POST | `/calendars/import-url` | calendars:write | Import from iCal URL |
+| GET | `/cal/{token}/feed.ics` | None (public) | Public iCal feed |
 
 ## Project Structure