Tests: add integration coverage for GET /places

[koinsaari]

GET /places has only unit tests for invalid inputs. The three real branches — proximity (lng/lat/radius), bounding box, and default 100-most-recent — have no integration coverage.

Suggested coverage

• Seed a handful of places at known coordinates, then assert:
  • Proximity: only places within radius are returned, ordering by distance is sane.
  • Bounding box: only places inside the envelope are returned.
  • Default: returns up to 100 places ordered by updated_at DESC.
  • Each branch returns the place's accessibility profile via Preload.
• File: extend cmd/api/integration_test.go.