Add legal assessment skill

[jkeussen]

Summary

Add a legal risk assessment skill that helps users identify, score, classify, and mitigate legal risks using a structured Severity × Likelihood framework. The skill includes guardrails for legal review, jurisdiction-sensitive scoring, and confidential handling of assessment inputs.

Changes

• Skill catalog — Register the legal-risk-assessment skill with discovery copy covering legal exposure, risk registers, risk matrices, compliance reviews, DPIAs, and required qualified legal review.
• Legal risk workflow — Add a new skill that guides scope definition, risk identification, scoring, mitigation planning, register creation, periodic review, and output formatting.
• Reference materials — Add category, scoring, and worked-example references to support consistent legal risk identification, qualitative scoring, risk bands, mitigation plans, and review cadence.

[stilla]

Merge readiness check

Done:

• (nothing yet — no CI configured on this repo)

Outstanding:

• Zero reviews, zero comments in ~99 days open
• Mergeable state: BLOCKED, likely branch protection requiring an approval that's never been given
• No requested reviewers

_{Sent by @jkeussen from a run of PR Merge Readiness Checker.}

[stilla]

Close to merging

Done:

• No CI configured for this repo, so nothing to fail
• No merge conflicts
• No changes requested

Outstanding:

• Waiting on a single approval (branch protection requires review; zero reviews have been posted so far, no reviewer requested)

Note: this PR has been open 100+ days with zero review engagement, so the "single approval" gap has sat unaddressed for a long time. Worth flagging for a reviewer if this hasn't moved on its own.

_{Sent by @jkeussen from a run of PR Merge Readiness Checker.}