Backend: - Add ai_provider + ai_model columns to APIClient model - New admin_ai router: GET /admin/api/ai/status + POST /admin/api/ai/test - Update ai_vision.py: provider_override + model_override support - Update pipeline: load client AI prefs for image processing - ClientUpdate/ClientResponse schemas include ai_provider/ai_model Frontend: - New AIConfigSection component: provider list, model dropdowns, test button with live results (no page refresh needed) - AI types (ai.types.ts) + API (api/ai.ts) - APIClient types extended with ai_provider/ai_model