Add automatic update checks for security tools (zizmor, SFW)

[John-David Dalton (jdalton)]

Summary

• Adds update.mts script that checks for new zizmor and SFW releases
• Respects pnpm minimumReleaseAge cooldown for third-party tools (zizmor)
• Updates Socket-owned tools (SFW) immediately without cooldown
• Updates embedded SHA-256 checksums in index.mts when new versions are found
• Adds phases 3b (security tools) and 3c (Claude Code version sync) to the updating skill

Files

• .claude/hooks/setup-security-tools/update.mts - Version check and checksum update script
• .claude/skills/updating/SKILL.md - Added phases 3b and 3c
• .gitignore - Updated to track .claude/hooks/ and .claude/settings.json

Test plan

• Run node .claude/hooks/setup-security-tools/update.mts and verify it checks versions
• Verify zizmor cooldown is respected (skips if release is too new)
• Verify SFW checksums are checked without cooldown
• Verify /update skill document includes the new phases