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-beyondcorp-zero-trust-access-model/references/api-reference.md

@@ -0,0 +1,57 @@
+# API Reference: BeyondCorp Zero Trust Assessment Agent
+
+## Dependencies
+
+| Library | Version | Purpose |
+|---------|---------|---------|
+| requests | >=2.28 | HTTP client for Google Cloud IAP and Access Context Manager APIs |
+
+## CLI Usage
+
+```bash
+python scripts/agent.py \
+  --project my-gcp-project \
+  --output-dir /reports/ \
+  --output beyondcorp_report.json
+```
+
+## Functions
+
+### `get_gcloud_token() -> str`
+Runs `gcloud auth print-access-token` to obtain Bearer token.
+
+### `list_iap_resources(project_id, token) -> list`
+GET IAP tunnel destination groups for the project.
+
+### `get_iap_settings(project_id, resource, token) -> dict`
+GET IAP settings for a specific compute service resource.
+
+### `list_access_levels(org_id, policy_name, token) -> list`
+GET `/accessPolicies/{name}/accessLevels` from Access Context Manager.
+
+### `audit_iap_bindings(project_id, token) -> list`
+POST `getIamPolicy` and filters for IAP-related role bindings.
+
+### `assess_zero_trust_posture(project_id, token) -> dict`
+Evaluates IAP coverage, binding security, checks for allUsers exposure.
+
+### `generate_report(project_id, token) -> dict`
+Computes zero trust score (0-100) based on findings.
+
+## Google Cloud APIs Used
+
+| API | Endpoint |
+|-----|----------|
+| IAP | `iap.googleapis.com/v1/projects/{id}/iap_tunnel/...` |
+| Access Context Manager | `accesscontextmanager.googleapis.com/v1/accessPolicies/...` |
+| Resource Manager | `cloudresourcemanager.googleapis.com/v1/projects/{id}:getIamPolicy` |
+
+## Output Schema
+
+```json
+{
+  "project": "my-project",
+  "posture": {"iap_resources": 5, "findings": []},
+  "zero_trust_score": 85
+}
+```