docs: add react-auth, react-openapi, vet sites; update standards registry and MCP setup

vet/mcp/modules/Header.json

@@ -0,0 +1,16 @@
+{
+  "module": "Header",
+  "content": {
+    "path": "Header",
+    "docstring": "Top navigation bar for the Veterinary Clinic demo app.\r\n\r\nA fixed `AppBar` with blurred translucent background and bottom divider,\r\nshowing the app title/logo and an Admin button. Rendered once by `main.jsx`\r\nabove the routed content; the title navigates to `/` and the Admin button to\r\n`/admin`.",
+    "objects": {
+      "Header": {
+        "name": "Header",
+        "kind": "component",
+        "path": "Header.Header",
+        "signature": "default(): React.JSX.Element",
+        "docstring": "Fixed top app bar with the title/logo and an Admin button.\r\n\r\nUses `useNavigate`, so it must be rendered inside a router. Clicking the\r\ntitle navigates to `/`; the Admin button navigates to `/admin`.\n\n**Returns:**\n\nThe header `AppBar` element."
+      }
+    }
+  }
+}