Return the curated chip catalog rendered on the Storyflo /search landing page.

This is the source of truth — the BE boot-warming task reads from the same module (:mod:app.search_chips) so chip→warming drift can never reappear. A follow-up FE PR will replace the hardcoded chip array in storyflo/app/search/page.tsx with a fetch against this endpoint; until then, the FE array and this endpoint are mirrored verbatim in :mod:app.search_chips.CURATED_SEARCH_CHIP_GROUPS.

Response shape::

{
  "groups": [
    {"group": "Markets", "topics": ["SpaceX", "Polymarket", ...]},
    {"group": "Sports",  "topics": ["World Cup", ...]},
    ...
  ],
  "all_queries": ["SpaceX", "Polymarket", ..., "news", "bitcoin", ...]
}

all_queries is the deduplicated union of curated chips + popular-keyword watchdog set, in the same order the boot warmer iterates so an FE caller can debug "is my chip in the warm set?" visually.

Public read-only — no auth, no per-user gating. Safe to cache at the CDN edge for hours.