Full `nix flake check` (CI) runs the treefmt formatting derivation. While the
hive-ci runner was offline (#1221), PRs merged without it, leaving 5 files
unformatted: hive-ag3nt/src/web_ui.rs, hive-c0re/src/bin/hivectl.rs,
hive-c0re/src/knowledge.rs, hive-c0re/src/matrix.rs,
hive-forge/src/verbs/attachment_get.rs. `nix fmt` output, pure formatting.
20c5039156