Added audit skill for security and further penetration testing purpose.

[kanatat-asp]

Summary
Adds a new kgraph audit command that scans existing repo maps and surfaces security-sensitive files and symbols grouped by category.
Introduces 6 built-in audit categories: Authentication & Authorization, Input Handling, Cryptography, Data Access, External Connections, and Dangerous Patterns.
Supports --json flag for machine-readable output, consistent with impact and context commands.

New files:
src/context/audit.ts — pure analysis function, scans file paths and symbol names against 6 security categories
src/cli/commands/audit.ts — command registration + markdown renderer

Modified files:
src/cli/index.ts — imports and registers registerAuditCommand
src/cli/help.ts — adds audit to the Workflows section

Usage:
kgraph audit # markdown output
kgraph audit --json # machine-readable

Test plan

• kgraph scan on a repo with auth/crypto/route code, then kgraph audit — verify findings appear per category
• kgraph audit --json — verify valid JSON output with categories, totalFlaggedFiles, totalFlaggedSymbols
• Repo with no matching symbols — verify "No security-sensitive patterns found" message
• kgraph --help — verify audit appears under Workflows section

[kentwynn]

Please add unit test and resolved conflict

[kentwynn]

Instead of introduce new cli command, please check current command as kgraph impact...