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/detecting-arp-poisoning-in-network-traffic/references/api-reference.md

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+# ARP Poisoning Detection — API Reference
+
+## Libraries
+
+| Library | Install | Purpose |
+|---------|---------|---------|
+| scapy | `pip install scapy` | PCAP parsing and ARP packet analysis |
+
+## Scapy ARP Packet Fields
+
+| Field | Description |
+|-------|-------------|
+| `op` | Operation: 1=request, 2=reply |
+| `hwsrc` | Source MAC address |
+| `psrc` | Source IP address |
+| `hwdst` | Destination MAC address |
+| `pdst` | Destination IP address |
+
+## ARP Spoofing Indicators
+
+| Indicator | Description | Severity |
+|-----------|-------------|----------|
+| Duplicate MACs for IP | Same IP mapped to multiple MACs | CRITICAL |
+| MAC claiming many IPs | One MAC responding for 3+ IPs | HIGH |
+| Gratuitous ARP flood | Excessive unsolicited ARP replies | MEDIUM |
+| ARP flip-flop | IP/MAC mapping changes rapidly | HIGH |
+
+## Scapy PCAP Analysis
+
+```python
+from scapy.all import rdpcap, ARP
+packets = rdpcap("capture.pcap")
+arp_replies = [p for p in packets if ARP in p and p[ARP].op == 2]
+```
+
+## System ARP Table
+
+```bash
+arp -a                  # Display ARP table
+arp -d <ip>            # Delete ARP entry
+ip neigh show          # Linux: show neighbor table
+```
+
+## arpwatch Database Format
+
+```
+<mac>\t<ip>\t<timestamp>\t<hostname>
+```
+
+## Detection Tools
+
+| Tool | Description |
+|------|-------------|
+| arpwatch | Monitors ARP table changes, emails on flip-flop |
+| arpsnitch | Real-time ARP spoofing alert |
+| XArp | Advanced ARP spoofing detection |
+| Snort rule | `alert arp any any -> any any (msg:"ARP spoof"; ...)` |
+
+## External References
+
+- [Scapy Documentation](https://scapy.readthedocs.io/)
+- [arpwatch Manual](https://linux.die.net/man/8/arpwatch)
+- [MITRE T1557.002 — ARP Cache Poisoning](https://attack.mitre.org/techniques/T1557/002/)