Add /api/plugins/settings-routes to OpenAPI spec

Document new endpoint that exposes plugin-contributed settings routes
for dynamic frontend UI extension.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

docs/openapi.json

@@ -3604,6 +3604,39 @@
     }
    }
   },
+  "/api/plugins/settings-routes": {
+   "get": {
+    "tags": [
+     "core-platform"
+    ],
+    "summary": "Settings routes contributed by enabled plugins for dynamic UI extension",
+    "description": "Returns settings routes from all enabled plugins via get_settings_routes() hook. Frontend router merges these to add plugin tabs/pages to settings hubs like Model Catalog.\n\n**Auth:** none (jwt-optional decorator, deliberately anonymous so unauthenticated pages can load plugin routes)\n\n**Params:** none\n\n**Example:**\n```\ncurl http://localhost:5001/api/plugins/settings-routes\n```",
+    "security": [
+     {},
+     {
+      "bearerAuth": []
+     }
+    ],
+    "responses": {
+     "200": {
+      "description": "Success. Body is the success_response envelope: {status, data, meta}.",
+      "content": {
+       "application/json": {
+        "$ref": "#/components/schemas/SuccessEnvelope"
+       }
+      }
+     },
+     "default": {
+      "description": "Error. Body is the error envelope; the code and message are nested under data.error.",
+      "content": {
+       "application/json": {
+        "$ref": "#/components/schemas/ErrorEnvelope"
+       }
+      }
+     }
+    }
+   }
+  },
   "/api/plugins/{name}": {
    "put": {
     "tags": [