feat(drill): the staging drill, the week before each forced wipe (stage 9c, D307-D309, D317-D319)

A Gitea job that checks each new Rust staging build in the seven days before the
monthly forced wipe:

- tools/drill/static.sh: staging's managed assemblies (DepotDownloader) and
  Oxide's staging build; whether Oxide has caught up (fieldlist --oxide-behind),
  the swap's field list compared, and the plugin compiled.
- tools/drill/drill.js: window (D318), gate (one check per depot manifest),
  live (rust-staging runs rnt.run all; rust-carbon is stopped and restarted when
  both 6000-map rigs run, D309) and report (one issue per build, state on the
  drill branch; a build waits up to three days for Oxide, D317).
- tools/drill/rig-start.sh: the rig's startup; installs the branch and Oxide's
  build for it, and refuses to start a mismatched pair.
- RunicNpcTest 0.7.2: stage 5's five fights look for a field with room for their
  280 m line (D319), and the spawn check names what did not spawn.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E14m6SuuY6i1vASFeGDBeY

.gitattributes

@@ -0,0 +1,2 @@
+# Shell scripts run on Linux (the CI runner, the staging rig): a CRLF checkout breaks them.
+*.sh text eol=lf