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/implementing-mtls-for-zero-trust-services/SKILL.md

@@ -1,16 +1,25 @@
 ---
 name: implementing-mtls-for-zero-trust-services
-description: >
-  Configures mutual TLS (mTLS) authentication between microservices using Python
-  cryptography library for certificate generation and ssl module for TLS verification.
-  Validates certificate chains, checks expiration, and audits mTLS deployment status.
-  Use when implementing zero-trust service-to-service authentication.
+description: 'Configures mutual TLS (mTLS) authentication between microservices using Python cryptography library for certificate
+  generation and ssl module for TLS verification. Validates certificate chains, checks expiration, and audits mTLS deployment
+  status. Use when implementing zero-trust service-to-service authentication.
+
+  '
 domain: cybersecurity
 subdomain: security-operations
-tags: [implementing, mtls, for, zero]
-version: "1.0"
+tags:
+- implementing
+- mtls
+- for
+- zero
+version: '1.0'
 author: mahipal
 license: Apache-2.0
+nist_csf:
+- DE.CM-01
+- RS.MA-01
+- GV.OV-01
+- DE.AE-02
 ---
 
 # Implementing mTLS for Zero Trust Services