feat: AI API Setting page with 4 provider sections and toggles

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>

apps/Frontend/src/components/layout/sidebar.tsx

@@ -276,7 +276,7 @@ export function Sidebar() {
             icon: <Phone className="h-4 w-4 text-gray-400" />,
           },
           {
-            name: "Google AI Settings",
+            name: "AI API Setting",
             path: "/settings/ai",
             icon: <Bot className="h-4 w-4 text-gray-400" />,
           },