Ports AjaxCalendarController::priceCalendarAction and priceTableAction
(MyE&P price config and price table), used on the /gruppe/gruppenhaus-*
pages and example trips. Page cache tags and "do not cache" on API
errors go through the frontend.cache.collector and
frontend.cache.instruction request attributes instead of TSFE.
Left out: priceConfig (no caller) and range (daytrip calendar via
bpn-connect, out of scope), so bpn-connect needs no credentials.
Co-Authored-By: Claude Opus 5.5 <[email protected]>