List organization notifications in the CLI #1108

Expose the new organization notifications endpoint from #1088 after its API layer.

Add a read-only cloud org notifications (Beta) command with limit, opaque cursor, severity, notification type, resource ID/type and RFC 3339 date filters. Preserve pagination metadata in JSON, render sparse responses safely for humans, declare permissions, and cover clap parsing and real-binary requests, OAuth and errors. Document page-by-page use and caller visibility.

Expose Client::notification_get_list; no new notification method is intentionally omitted. This extends the existing drift stack above #1099 and preserves all its changes. Add a read-only step to the organization integration suite; do not provision paid test services for it.

API prerequisite: #1104. Implementation draft: #1105 in native stack #1095.