docs: admin features missing from the docs site #384

Tracking issue for operator-facing features that landed in ricochet-rs/ricochet since v0.10.0 (2026-06-08) and have no entry under src/content/docs/dev/admin/.

Each sub-issue names the upstream pull request, the behaviour that is missing, and the page that should carry it.

Audit covers the 51 feat commits in v0.10.0..main.