chore(ci): remove the Claude Code Review workflow

[JayVDZ]

Description

Retires .github/workflows/claude-code-review.yml and its claude-review status check. Rationale: all PRs in this repository are already developed with Claude assistance, so the automated review was largely reviewing its own output, and the multi-agent review harness consumed roughly USD 15-equivalent of subscription usage per large PR (e.g. #1094: 16 minutes, 15 turns). The machine-enforced merge gates remain CodeQL (with github-code-quality review comments and blocking unresolved threads), build-and-test, base image scanning, and changelog lint; an AI-assisted review is still available on demand by commenting @claude review this PR (claude.yml is unchanged).

Documentation updated to match: required-check count and list in CLAUDE.md, the ruleset table and human-review paragraph in engineering/DEVELOPER_GUIDE.md, the automated-baseline-review control in engineering/COMPLIANCE_MAPPING.md, and the pr-merge skill's required-check list.

Note for the merger: claude-review must also be absent from the ruleset's required status checks (Settings → Rules → Rulesets) — it was removed this morning; if it has since been re-added, remove it again before or immediately after this merges, otherwise future PRs will wait on a check that no longer reports.

Type of change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Refactor (no functional change)
• Other (describe below): CI workflow removal plus documentation alignment

Testing

• Workflow YAML and Markdown only; no build/test applies (per repo build/test exceptions)
• Verified no claude-review / claude-code-review references remain outside git history

Documentation

• Engineering reference documentation updated (engineering/) where a design/architecture doc would otherwise be stale

Docs: n/a - CI/dev tooling change; engineering reference docs updated in this PR, no public docs affected

Screenshots / output (if applicable)

n/a

Checklist

• My commit messages are descriptive and reference the relevant Issue (if any)
• My code follows the conventions in docs/DEVELOPER_GUIDE.md
• User-facing text uses British English (en-GB)
• This PR does not include security-sensitive information (real credentials, customer data, internal hostnames)

Additional context

The CLAUDE_CODE_OAUTH_TOKEN secret stays in place — claude.yml (the @claude mention workflow) still uses it.

🤖 Generated with Claude Code

https://claude.ai/code/session_01SmxijKgLk22PXG2benH2i4

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Generated by Claude Code