Add OpenAPI docs, frontend, migrations, and API updates

- OpenAPI: add missing endpoints (add-from-url, subscriptions, public availability)
- OpenAPI: CalendarSubscription schema, Subscriptions tag
- Frontend app
- Migrations: count_for_availability, subscriptions_sync, user_preferences, calendar_settings
- Config, rate limit, auth, calendar, booking, ICS, availability, user service updates

Made-with: Cursor

sqlc/queries/subscriptions.sql

@@ -1,8 +1,31 @@
 -- name: CreateCalendarSubscription :one
-INSERT INTO calendar_subscriptions (id, calendar_id, source_url)
-VALUES ($1, $2, $3)
+INSERT INTO calendar_subscriptions (id, calendar_id, source_url, sync_interval_minutes)
+VALUES ($1, $2, $3, $4)
 RETURNING *;
 
--- name: GetSubscriptionByCalendar :one
+-- name: ListSubscriptionsByCalendar :many
 SELECT * FROM calendar_subscriptions
-WHERE calendar_id = $1;
+WHERE calendar_id = $1
+ORDER BY created_at ASC;
+
+-- name: GetSubscriptionByID :one
+SELECT * FROM calendar_subscriptions
+WHERE id = $1;
+
+-- name: DeleteSubscription :exec
+DELETE FROM calendar_subscriptions
+WHERE id = $1;
+
+-- name: UpdateSubscriptionLastSynced :exec
+UPDATE calendar_subscriptions
+SET last_synced_at = now()
+WHERE id = $1;
+
+-- name: ListSubscriptionsDueForSync :many
+SELECT s.id, s.calendar_id, s.source_url, c.owner_id
+FROM calendar_subscriptions s
+JOIN calendars c ON c.id = s.calendar_id AND c.deleted_at IS NULL
+WHERE s.sync_interval_minutes IS NOT NULL
+  AND s.sync_interval_minutes > 0
+  AND (s.last_synced_at IS NULL
+       OR s.last_synced_at + make_interval(mins => s.sync_interval_minutes::numeric) <= now());