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/repository/calendars.sql.go

@@ -91,6 +91,39 @@ func (q *Queries) GetCalendarByID(ctx context.Context, id pgtype.UUID) (GetCalen
 	return i, err
 }
 
+const getCalendarByPublicToken = `-- name: GetCalendarByPublicToken :one
+SELECT id, owner_id, name, color, is_public, public_token, created_at, updated_at
+FROM calendars
+WHERE public_token = $1 AND is_public = true AND deleted_at IS NULL
+`
+
+type GetCalendarByPublicTokenRow struct {
+	ID          pgtype.UUID        `json:"id"`
+	OwnerID     pgtype.UUID        `json:"owner_id"`
+	Name        string             `json:"name"`
+	Color       string             `json:"color"`
+	IsPublic    bool               `json:"is_public"`
+	PublicToken pgtype.Text        `json:"public_token"`
+	CreatedAt   pgtype.Timestamptz `json:"created_at"`
+	UpdatedAt   pgtype.Timestamptz `json:"updated_at"`
+}
+
+func (q *Queries) GetCalendarByPublicToken(ctx context.Context, publicToken pgtype.Text) (GetCalendarByPublicTokenRow, error) {
+	row := q.db.QueryRow(ctx, getCalendarByPublicToken, publicToken)
+	var i GetCalendarByPublicTokenRow
+	err := row.Scan(
+		&i.ID,
+		&i.OwnerID,
+		&i.Name,
+		&i.Color,
+		&i.IsPublic,
+		&i.PublicToken,
+		&i.CreatedAt,
+		&i.UpdatedAt,
+	)
+	return i, err
+}
+
 const listCalendarsByUser = `-- name: ListCalendarsByUser :many
 SELECT c.id, c.owner_id, c.name, c.color, c.is_public, c.created_at, c.updated_at, cm.role
 FROM calendars c
@@ -139,6 +172,22 @@ func (q *Queries) ListCalendarsByUser(ctx context.Context, userID pgtype.UUID) (
 	return items, nil
 }
 
+const setCalendarPublicToken = `-- name: SetCalendarPublicToken :exec
+UPDATE calendars
+SET public_token = $2, updated_at = now()
+WHERE id = $1 AND deleted_at IS NULL
+`
+
+type SetCalendarPublicTokenParams struct {
+	ID          pgtype.UUID `json:"id"`
+	PublicToken pgtype.Text `json:"public_token"`
+}
+
+func (q *Queries) SetCalendarPublicToken(ctx context.Context, arg SetCalendarPublicTokenParams) error {
+	_, err := q.db.Exec(ctx, setCalendarPublicToken, arg.ID, arg.PublicToken)
+	return err
+}
+
 const softDeleteCalendar = `-- name: SoftDeleteCalendar :exec
 UPDATE calendars SET deleted_at = now(), updated_at = now()
 WHERE id = $1 AND deleted_at IS NULL