Summary:
Adds the SubmitQueue Gateway List API to the service README API reference and includes a grpcurl example for listing recent requests by queue and time window.

Test Plan:
`make fmt`
STDOUT proof:
```
Formatting complete!
```

`make local-submitqueue-start`
STDOUT proof excerpt:
```
✅ Full stack is running!
  Gateway gRPC:      localhost:64687
  Orchestrator gRPC: localhost:64686
```

`grpcurl -plaintext -import-path . -proto api/submitqueue/gateway/proto/gateway.proto -d '{"queue":"test-queue","change":{"uris":["github://uber/docs-list/pull/2/abcdef0123456789abcdef0123456789abcdef02"]},"strategy":"REBASE"}' localhost:64687 uber.submitqueue.gateway.SubmitQueueGateway/Land`
STDOUT proof:
```json
{
  "sqid": "test-queue/1"
}
```

`grpcurl -plaintext -import-path . -proto api/submitqueue/gateway/proto/gateway.proto -d '{"queue":"test-queue","start_time_ms":1,"end_time_ms":9999999999999,"page_size":10}' localhost:64687 uber.submitqueue.gateway.SubmitQueueGateway/List`
STDOUT proof:
```json
{
  "requests": [
    {
      "sqid": "test-queue/1",
      "queue": "test-queue",
      "changeUris": [
        "github://uber/docs-list/pull/2/abcdef0123456789abcdef0123456789abcdef02"
      ],
      "status": "landed",
      "metadata": {
        "batch_id": "test-queue/batch/1"
      },
      "startedAtMs": "1783389642136",
      "updatedAtMs": "1783389644505",
      "completedAtMs": "1783389644505",
      "terminal": true
    }
  ]
}
```

`make local-stop`
STDOUT proof:
```
Services stopped. Data volumes preserved.
```