List uptime

Portfolio-level uptime listing: one row per monitored site with its current status and last ping, answering "is anything down right now" in a single call. Rolling availability windows for one site live in `Show site uptime` (`/sites/{site}/uptime`). JSON:API collection of type `site-uptimes`, id = the site's uptime service id. Each entry carries `site` (`id`, `name`), `enabled` (is the monitor on), `status` (`up` / `down` / `unknown`), `status_since` and `last_ping` (`at`, `status`, `status_code`, `response_time_ms`, `error`), plus the usual top-level `links`, `meta` and `jsonapi`. `last_ping` is null when the monitor has not pinged in the last 30 days. Example entry: ```json {"type":"site-uptimes","id":"1","attributes":{"site":{"id":1,"name":"Portfolio site"},"enabled":true,"status":"down","status_since":"2026-02-10T11:00:00.000000Z","last_ping":{"at":"2026-02-10T11:00:00.000000Z","status":"down","status_code":503,"response_time_ms":null,"error":"Server error"}}} ``` Default sort is `-status`, so outages come first. An unknown filter value or an out-of-range `page[size]` answers 422; a member without the uptime read permission answers 404. A read-only token is enough. The MCP twin of this endpoint is the `uptime-index` tool.