SupporterWallController

REST controller for the public Supporter Wall endpoint. Ships in feature/internal-membership-supporter-wall; message field added in feature/membership-launch-cleanup. Exposes GET /shows/{id}/supporter-wall — no authentication required. The message field in the response is zeroed out when the show’s _benecaster_show_supporter_wall_show_why_field toggle is off, even if a stored message exists. Delegates roster data fetching to SupporterWallQuery.