703c4b5edf
The feature_classroom_enabled flag was fully wired in backend
(classroom/sessions.js:11-14 returns 403 when '0', initialized in
legacy-migrate.js:870 to '1') but had no UI control — admin could
only flip it via direct SQL.
- adminController.updateFeatures: classroom was ALREADY in allowed list
- admin/sections/games.js: new toggle row with video icon added to GAME_FEATURES
- js/api.js hideDisabledFeatures: classroom path mapping added ('/classroom')
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>