chore(api): migrate chat endpoints to OpenAPI

apps/meteor/app/api/server/ajv.ts

@@ -3,6 +3,13 @@ import { ajv, ajvQuery } from '@rocket.chat/rest-typings';
 
 const components = schemas.components?.schemas;
 if (components) {
+	// Patch MessageAttachmentDefault to reject unknown properties so the oneOf
+	// discriminator works correctly (otherwise it matches every attachment).
+	const mad = components.MessageAttachmentDefault;
+	if (mad && typeof mad === 'object' && 'type' in mad) {
+		(mad as Record<string, unknown>).additionalProperties = false;
+	}
+
 	for (const key in components) {
 		if (Object.prototype.hasOwnProperty.call(components, key)) {
 			const uri = `#/components/schemas/${key}`;