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

internal/api/routes.go

@@ -43,6 +43,8 @@ func NewRouter(h Handlers, authMW *mw.AuthMiddleware, rateLimiter *mw.RateLimite
 
 		r.Get("/booking/{token}/availability", h.Booking.GetAvailability)
 		r.Post("/booking/{token}/reserve", h.Booking.Reserve)
+
+		r.Get("/cal/{token}/feed.ics", h.ICS.PublicFeed)
 	})
 
 	// Authenticated routes
@@ -68,6 +70,7 @@ func NewRouter(h Handlers, authMW *mw.AuthMiddleware, rateLimiter *mw.RateLimite
 			r.With(mw.RequireScope("calendars", "read")).Get("/", h.Calendar.List)
 			r.With(mw.RequireScope("calendars", "write")).Post("/", h.Calendar.Create)
 			r.With(mw.RequireScope("calendars", "write")).Post("/import", h.ICS.Import)
+			r.With(mw.RequireScope("calendars", "write")).Post("/import-url", h.ICS.ImportURL)
 
 			r.Route("/{id}", func(r chi.Router) {
 				r.With(mw.RequireScope("calendars", "read")).Get("/", h.Calendar.Get)