chore(agents): bump Claude Code version to 2.1.78 and extend gitleaks config

[8nevil8]

Summary

Bumps the Claude Code supported/minimum versions and enables the default gitleaks ruleset to strengthen secrets detection.

Changes

• CLAUDE_SUPPORTED_VERSION: 2.1.63 → 2.1.78
• CLAUDE_MINIMUM_SUPPORTED_VERSION: 2.1.53 → 2.1.60
• .gitleaks.toml: added [extend] useDefault = true to enable the default gitleaks ruleset; excluded dist/ build artifacts from scanning
• Fixed all gitleaks findings surfaced by the new ruleset:
  • Added // gitleaks:allow to intentional test data in security.test.ts
  • Replaced fake API keys with YOUR_API_KEY_HERE in best-practices.md and violation-examples.md
  • Replaced fake JWT tokens with <YOUR_JWT_TOKEN> in AUTHENTICATION.md
  • Replaced fake key in unit-tester-agent.md with non-triggering placeholder

Impact

• Claude Code 2.1.60–2.1.78 will be accepted; older versions blocked
• Secrets scanning now uses the full default gitleaks ruleset (previously no rules were active)

Checklist

• Self-reviewed
• Manual testing performed
• Documentation updated (if needed)
• No breaking changes (or clearly documented)