chore: Gitignore agent skill auto-update artifacts (#109302)

Adds `.agents/.gitignore` and `agents.lock` to the root `.gitignore` so
that
dotagents auto-updates don't leave dirty working tree state. These files
are
auto-generated and shouldn't be tracked.

Also mirrors the current `.agents/.gitignore` skill entries (prefixed
with
`.agents/`) as a temporary fallback to avoid breaking pre-existing
installs
during the migration. These temporary entries can be removed after a
week.

Both `.agents/.gitignore` and `agents.lock` are removed from git
tracking
via `git rm --cached`.


Agent transcript:
https://claudescope.sentry.dev/share/Wh40JwobL_ulw3REzVDMrPgv1qLRY2vrz-_mzK2hoqU

Author: gricha

.agents/.gitignore

@@ -65,3 +65,31 @@ yarn.lock
 .claude/settings.local.json
 .claude/plans
 .warden/
+# Auto-updated agent skill dependencies — ignore to avoid dirty state
+.agents/.gitignore
+agents.lock
+# end
+
+# Temporary: mirror .agents/.gitignore contents to avoid breaking pre-existing installs. Remove that after a week
+.agents/skills/agents-md/
+.agents/skills/blog-writing-guide/
+.agents/skills/brand-guidelines/
+.agents/skills/claude-settings-audit/
+.agents/skills/code-review/
+.agents/skills/code-simplifier/
+.agents/skills/commit/
+.agents/skills/create-pr/
+.agents/skills/django-access-review/
+.agents/skills/django-perf-review/
+.agents/skills/doc-coauthoring/
+.agents/skills/find-bugs/
+.agents/skills/gh-review-requests/
+.agents/skills/iterate-pr/
+.agents/skills/security-review/
+.agents/skills/skill-creator/
+.agents/skills/skill-scanner/
+.agents/skills/sred-project-organizer/
+.agents/skills/sred-work-summary/
+.agents/skills/warden/
+.agents/skills/warden-sweep/
+# end