Add OpenAI, Claude AI, and DentalManagement AI sections to the AI API Setting page, each with a masked API key input and an on/off toggle (defaulting to off). Rename sidebar label from "Google AI Settings" to "AI API Setting". Add provider-key and provider-enabled backend endpoints and extend the AiSettings schema with 6 new fields. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>