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/hunting-for-dns-based-persistence/SKILL.md

@@ -1,12 +1,25 @@
 ---
 name: hunting-for-dns-based-persistence
-description: Hunt for DNS-based persistence mechanisms including DNS hijacking, dangling CNAME records, wildcard DNS abuse, and unauthorized zone modifications using passive DNS databases, SecurityTrails API, and DNS audit log analysis.
+description: Hunt for DNS-based persistence mechanisms including DNS hijacking, dangling CNAME records, wildcard DNS abuse,
+  and unauthorized zone modifications using passive DNS databases, SecurityTrails API, and DNS audit log analysis.
 domain: cybersecurity
 subdomain: threat-hunting
-tags: [dns, persistence, threat-hunting, passive-dns, dns-hijacking, subdomain-takeover, securitytrails]
-version: "1.0"
+tags:
+- dns
+- persistence
+- threat-hunting
+- passive-dns
+- dns-hijacking
+- subdomain-takeover
+- securitytrails
+version: '1.0'
 author: mahipal
 license: Apache-2.0
+nist_csf:
+- DE.CM-01
+- DE.AE-02
+- DE.AE-07
+- ID.RA-05
 ---
 
 # Hunting for DNS-based Persistence