Docs: align runbook safety checks with editor skill

[dknauss]

Summary

• correct the remaining singular --field WP-CLI examples in the security-breach response flow
• normalize the cache-plugin annotation string to the exact runbook-skill form
• add explicit warning/approval markers around additional side-effect commands flagged by the runbook-skill audit
• refresh docs/current-metrics.md and CHANGELOG.md to match the edited source

Why

A skill-validation pass against an older runbook snapshot and the current canonical runbook showed that the current document was much better than the legacy version, but still had a few residual issues the revised wordpress-runbook-ops skill correctly surfaced:

• singular --field examples in the credential/session reset flow
• cache-plugin annotation drift from the current exact string
• several unmarked side-effect commands in migration, restore, cache, option, transient, and test-email procedures

This PR addresses those current-runbook findings without attempting a wholesale structural rewrite of the document into the skill's stricter full procedure template.

Validation

• bash .github/scripts/verify-metrics.sh
• focused post-patch skill audit: residual warning-gap heuristic dropped from 29 to 10
• focused post-patch skill audit: residual known WP-CLI flag regressions dropped from 2 to 0
• focused post-patch skill audit: cache-plugin annotation exact-string matches increased from 0 to 6

Artifact generation

Local full regeneration was blocked in this session because xelatex is not installed. To cover that, I dispatched the repository workflow on this branch:

• Generate PDF, Word & EPUB Documents run

Notes

This PR improves skill alignment materially, but the broader fit gap remains: the canonical runbook still does not use the stricter ### Procedure Metadata / ### Commands / ### Verification heading model that the current skill prefers.

[chatgpt-codex-connector]

You have reached your Codex usage limits for code reviews. You can see your limits in the Codex usage dashboard.
To continue using code reviews, you can upgrade your account or add credits to your account and enable them for code reviews in your settings.