fix(mcp): use JSON-compatible invitation dates (#6814)

apps/docs/static/api/open-api-schema.json

@@ -2572,7 +2572,9 @@
                 "type": "object",
                 "properties": {
                   "expirationDate": {
-                    "type": "string"
+                    "type": "string",
+                    "format": "date-time",
+                    "pattern": "^(?:(?:\\d\\d[2468][048]|\\d\\d[13579][26]|\\d\\d0[48]|[02468][048]00|[13579][26]00)-02-29|\\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\\d|30)|(?:02)-(?:0[1-9]|1\\d|2[0-8])))T(?:(?:[01]\\d|2[0-3]):[0-5]\\d(?::[0-5]\\d(?:\\.\\d+)?)?(?:Z|([+-](?:[01]\\d|2[0-3]):[0-5]\\d)))$"
                   }
                 },
                 "required": [