Complete folder anatomy for all 649 cybersecurity skills + update LICENSE to Mahipal

- Add scripts/agent.py and references/api-reference.md to all remaining skills
- Update all 648 LICENSE files: copyright now reads 'Mahipal'
- Add implementing-security-monitoring-with-datadog (new skill with full anatomy)
- All 649 skills now have: SKILL.md, LICENSE, scripts/agent.py, references/api-reference.md

skills/performing-authenticated-vulnerability-scan/references/api-reference.md

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+# Authenticated Vulnerability Scan — API Reference
+
+## Libraries
+
+| Library | Install | Purpose |
+|---------|---------|---------|
+| requests | `pip install requests` | Nessus REST API client |
+
+## Nessus REST API Authentication
+
+```
+Header: X-ApiKeys: accessKey=<key>; secretKey=<key>
+```
+
+## Nessus API Endpoints
+
+| Method | Endpoint | Description |
+|--------|----------|-------------|
+| GET | `/scans` | List all scans |
+| GET | `/scans/{id}` | Scan details with results |
+| GET | `/scans/{id}/hosts/{host_id}` | Per-host vulnerability details |
+| POST | `/scans` | Create new scan |
+| POST | `/scans/{id}/launch` | Launch existing scan |
+| POST | `/scans/{id}/export` | Export results (nessus/csv/html) |
+| GET | `/policies` | List scan policies |
+| GET | `/credentials` | List stored credentials |
+
+## Severity Levels
+
+| Index | Name | CVSS Range |
+|-------|------|-----------|
+| 4 | Critical | 9.0 - 10.0 |
+| 3 | High | 7.0 - 8.9 |
+| 2 | Medium | 4.0 - 6.9 |
+| 1 | Low | 0.1 - 3.9 |
+| 0 | Info | Informational |
+
+## Credential Types for Authenticated Scans
+
+| Type | Protocol | Checks Enabled |
+|------|----------|---------------|
+| SSH | Linux/macOS | Package versions, file permissions, configs |
+| SMB | Windows | Patch levels, registry, installed software |
+| ESXi | VMware | Hypervisor patches, VM configurations |
+| SNMP | Network devices | Device firmware, community string audit |
+| Database | SQL Server/Oracle | DB-level patches, user permissions |
+
+## Key Nessus Plugin Families
+
+| Family | Description |
+|--------|-------------|
+| Windows: Microsoft Bulletins | Microsoft security patches |
+| Ubuntu Local Security Checks | Ubuntu package vulnerabilities |
+| CGI abuses | Web application vulnerabilities |
+| Misc. | Miscellaneous security checks |
+| Service detection | Network service identification |
+
+## External References
+
+- [Nessus REST API Docs](https://docs.tenable.com/nessus/Content/API.htm)
+- [Tenable Developer Portal](https://developer.tenable.com/)
+- [Nessus Credentialed Scanning](https://docs.tenable.com/nessus/Content/CredentialedChecksOnWindows.htm)