caveman plugin: off-by-default opt-in guard (repo + user CAVEMAN_DEFAULT_MODE=off) ...

Installed the third-party caveman Claude Code plugin (user scope) per operator
direction, then guarded it off-by-default so it never auto-arms while operating
the cloud. Hooks inspected read-only first: purely behavioral, no network /
credential access. Repo .claude/settings.json carries env CAVEMAN_DEFAULT_MODE=off
(durable, shared); the same guard was added to ~/.claude/settings.json (out of
repo, not committed) for off-by-default across all repos. /caveman still
activates on demand for future hardened-workflow deployment testing.

Harness-config only: no cloud mutation, no status change (CURRENT-STATE
untouched), repo-lint 0 fail. Changelog: docs/changelog-20260723-caveman-optin-guard.md.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VUjEb7onHpdqFHUnio6iVw