chore: update OpenAPI spec from monorepo (#579)

Co-authored-by: OpenRouter SDK Bot <sdk-bot@openrouter.ai>

Author: openrouter-docs-sync[bot]

.speakeasy/in.openapi.yaml

@@ -10989,6 +10989,11 @@ components:
                             type: 'array'
                           - type: 'string'
                           - type: 'null'
+                      type:
+                        default: 'message'
+                        enum:
+                          - 'message'
+                        type: 'string'
                     type: 'object'
                 description: 'An output message item'
                 example: