Add cryptographic agility migration gates

[Dolpme]

Summary

• add cryptographic agility migration gates to secure-code-review Step 5
• add SCR-CRYPTO-AGILITY-* finding IDs for artifact metadata, centralized policy, tested migration paths, bounded legacy fallback, fail-closed downgrade handling, fixtures, and telemetry
• add a Cryptographic Agility Evidence table to the review output format

Related issue

Closes #1675

Validation

• git diff --check
• frontmatter required-field check for all skills/ and roles/ SKILL.md files
• index.yaml referenced-file check
• diff scan for prompt-injection/private/payment/wallet text
• Markdown fence-balance check for edited file
• targeted marker coverage for cryptographic agility requirements
• official reference HTTP 200 checks for OWASP Cryptographic Storage Cheat Sheet and NIST SP 800-131A