List runs

Return the caller's own runs, newest first. Projected from the indexed run row rather than folded from the event log, so it omits outputs and reason and reports a suspended run as running — read GET /runs/{id} for a single run in full. Rate limiting: reads are not metered per-key today — only POST /runs is (60/minute). Reads may become metered without a breaking change, so treat 429 with Retry-After as possible on any endpoint and back off rather than polling in a tight loop. For run progress prefer GET /runs/{id}/stream, or poll GET /runs/{id} no more than once per second.