Part of the tracker-tag cleanup: the hive convention is prose, not
issue-tracker tags, in code. Reword the 21 tags in the nix tree
(flake.nix + the hive-c0re/ci/gateway/network modules) to describe
the thing they pointed at, preserving the context without the tag.
Comment-only — no eval or logic change. Validated with nix fmt
(no reformatting) and nix flake check --no-build (all checks
evaluate clean); the full build check was skipped locally because
the shared remote builder is degraded, so CI will exercise the
build derivations once the runner recovers.