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/implementing-dmarc-dkim-spf-email-security/references/api-reference.md

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+# API Reference: Implementing DMARC/DKIM/SPF Email Security
+
+## dnspython Lookups
+
+```python
+import dns.resolver
+# SPF
+answers = dns.resolver.resolve("example.com", "TXT")
+# DMARC
+answers = dns.resolver.resolve("_dmarc.example.com", "TXT")
+# DKIM
+answers = dns.resolver.resolve("selector._domainkey.example.com", "TXT")
+```
+
+## SPF Record Syntax
+
+| Mechanism | Example | Meaning |
+|-----------|---------|---------|
+| `include:` | `include:_spf.google.com` | Authorize sender |
+| `ip4:` | `ip4:203.0.113.0/24` | Allow IP range |
+| `-all` | End of record | Hard fail others |
+| `~all` | End of record | Soft fail (weak) |
+| `+all` | End of record | Allow all (insecure) |
+
+## DMARC Policy Levels
+
+| Policy | Action | Severity if Missing |
+|--------|--------|---------------------|
+| `p=reject` | Reject failing mail | Recommended |
+| `p=quarantine` | Send to spam | Acceptable |
+| `p=none` | Monitor only | HIGH risk |
+
+## Recommended DNS Records
+
+```
+# SPF
+v=spf1 include:_spf.google.com -all
+
+# DMARC
+v=DMARC1; p=reject; pct=100; rua=mailto:dmarc@example.com; adkim=s; aspf=s
+
+# DKIM (provider-specific key)
+selector._domainkey.example.com TXT "v=DKIM1; k=rsa; p=MIIBIjAN..."
+```
+
+### References
+
+- SPF RFC 7208: https://www.rfc-editor.org/rfc/rfc7208
+- DMARC RFC 7489: https://www.rfc-editor.org/rfc/rfc7489
+- DKIM RFC 6376: https://www.rfc-editor.org/rfc/rfc6376
+- dnspython: https://dnspython.readthedocs.io/