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/implementing-bgp-security-with-rpki/references/api-reference.md

@@ -0,0 +1,56 @@
+# API Reference: BGP RPKI Validation Agent
+
+## Dependencies
+
+| Library | Version | Purpose |
+|---------|---------|---------|
+| requests | >=2.28 | HTTP client for RIPEstat and Cloudflare RPKI APIs |
+
+## CLI Usage
+
+```bash
+python scripts/agent.py \
+  --asn AS13335 \
+  --prefixes 1.1.1.0/24 104.16.0.0/12 \
+  --output-dir /reports/ \
+  --output rpki_report.json
+```
+
+## Functions
+
+### `validate_prefix_rpki(prefix) -> dict`
+Queries RIPEstat `/rpki-validation/data.json` for RPKI status (valid/invalid/unknown).
+
+### `get_roas_for_asn(asn) -> list`
+Queries Cloudflare RPKI `/api/v1/roas` for Route Origin Authorizations.
+
+### `get_prefix_overview(prefix) -> dict`
+Queries RIPEstat `/prefix-overview/data.json` for routing overview.
+
+### `check_rpki_adoption(asn) -> dict`
+Compares announced prefixes against ROA coverage to calculate adoption percentage.
+
+### `validate_multiple_prefixes(prefixes) -> list`
+Batch validates prefixes against RPKI.
+
+### `generate_report(asn, prefixes) -> dict`
+Full report with adoption metrics, per-prefix validation, and recommendations.
+
+## APIs Used
+
+| API | Endpoint |
+|-----|----------|
+| RIPEstat | `stat.ripe.net/data/rpki-validation/data.json` |
+| RIPEstat | `stat.ripe.net/data/announced-prefixes/data.json` |
+| Cloudflare RPKI | `rpki.cloudflare.com/api/v1/roas` |
+
+## Output Schema
+
+```json
+{
+  "asn": "AS13335",
+  "adoption": {"announced_prefixes": 500, "roa_covered": 498, "coverage_pct": 99.6},
+  "prefix_validation": [{"prefix": "1.1.1.0/24", "status": "valid"}],
+  "recommendations": ["Create ROAs for 2 uncovered prefixes"]
+}
+```