Add folder anatomy (scripts/agent.py + references/api-reference.md) for 648 cybersecurity skills

Complete skill folder anatomy across all cybersecurity skills:
- scripts/agent.py: 80-150 line Python agents using real libraries (impacket,
  boto3, azure-mgmt-*, kubernetes, pefile, yara, scapy, shodan, stix2, etc.)
- references/api-reference.md: real API documentation with method signatures
- LICENSE: MIT license for all skill folders

skills/exploiting-ipv6-vulnerabilities/references/api-reference.md

@@ -0,0 +1,59 @@
+# API Reference: IPv6 Vulnerability Assessment Agent
+
+## Dependencies
+
+| Library | Version | Purpose |
+|---------|---------|---------|
+| scapy | >=2.5 | IPv6 packet crafting, NDP analysis, RA capture |
+
+## CLI Usage
+
+```bash
+sudo python scripts/agent.py \
+  --interface eth0 \
+  --known-routers "fe80::1" "fe80::2" \
+  --output ipv6_report.json
+```
+
+## Functions
+
+### `discover_ipv6_hosts(interface, timeout) -> list`
+Sends ICMPv6 Echo Request to `ff02::1` (all-nodes multicast) and collects replies.
+
+### `capture_router_advertisements(interface, timeout) -> list`
+Sniffs ICMPv6 type 134 (Router Advertisements) and extracts prefix info, DNS servers, and flags.
+
+### `detect_rogue_ra(ras, known_routers) -> list`
+Compares RA source addresses against a known-router allowlist. Unrecognized sources flagged as rogue.
+
+### `check_ipv6_firewall() -> dict`
+Runs `ip6tables -L -n` to check for IPv6 firewall rules. Empty ruleset is flagged.
+
+### `check_tunnel_protocols(interface, timeout) -> dict`
+Sniffs for Teredo (UDP 3544), 6to4 (IP proto 41), and ISATAP tunnel traffic.
+
+### `generate_assessment(interface, known_routers) -> dict`
+Orchestrates all checks and produces the final assessment report.
+
+## Scapy Layers Used
+
+| Layer | Purpose |
+|-------|---------|
+| `ICMPv6ND_RA` | Router Advertisement parsing |
+| `ICMPv6NDOptPrefixInfo` | Prefix information extraction |
+| `ICMPv6NDOptRDNSS` | DNS server option extraction |
+| `ICMPv6EchoRequest` | Multicast host discovery |
+
+## Output Schema
+
+```json
+{
+  "interface": "eth0",
+  "ipv6_hosts_discovered": 15,
+  "router_advertisements": [{"src_ip": "fe80::1", "router_lifetime": 1800}],
+  "rogue_ras": [],
+  "firewall_status": {"rules_count": 0},
+  "tunnel_protocols": {"teredo": false},
+  "risk_findings": ["HIGH: No ip6tables rules configured"]
+}
+```