feat: add NIST CSF 2.0 nist_csf field to all 754 cybersecurity skills

Mapped every skill to NIST CSF 2.0 subcategory IDs (GV/ID/PR/DE/RS/RC functions)
based on subdomain and content analysis. Restores 11 skills corrupted during
prior rebase, re-enriching with ATLAS, D3FEND, NIST AI RMF, and CSF 2.0 fields.

All 754 skills now carry structured mappings for all 5 security frameworks:
- MITRE ATT&CK (in tags)
- MITRE ATLAS v5.5 (atlas_techniques)
- MITRE D3FEND v1.3 (d3fend_techniques)
- NIST AI RMF 1.0 (nist_ai_rmf)
- NIST CSF 2.0 (nist_csf)

skills/securing-api-gateway-with-aws-waf/SKILL.md

@@ -1,15 +1,28 @@
 ---
 name: securing-api-gateway-with-aws-waf
-description: >
-  Securing API Gateway endpoints with AWS WAF by configuring managed rule groups for
-  OWASP Top 10 protection, creating custom rate limiting rules, implementing bot control,
-  setting up IP reputation filtering, and monitoring WAF metrics for security effectiveness.
+description: 'Securing API Gateway endpoints with AWS WAF by configuring managed rule groups for OWASP Top 10 protection,
+  creating custom rate limiting rules, implementing bot control, setting up IP reputation filtering, and monitoring WAF metrics
+  for security effectiveness.
+
+  '
 domain: cybersecurity
 subdomain: cloud-security
-tags: [cloud-security, aws, waf, api-gateway, rate-limiting, bot-protection, owasp]
-version: "1.0"
+tags:
+- cloud-security
+- aws
+- waf
+- api-gateway
+- rate-limiting
+- bot-protection
+- owasp
+version: '1.0'
 author: mahipal
 license: Apache-2.0
+nist_csf:
+- PR.IR-01
+- ID.AM-08
+- GV.SC-06
+- DE.CM-01
 ---
 
 # Securing API Gateway with AWS WAF