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/investigating-ransomware-attack-artifacts/SKILL.md

@@ -1,12 +1,24 @@
 ---
 name: investigating-ransomware-attack-artifacts
-description: Identify, collect, and analyze ransomware attack artifacts to determine the variant, initial access vector, encryption scope, and recovery options.
+description: Identify, collect, and analyze ransomware attack artifacts to determine the variant, initial access vector, encryption
+  scope, and recovery options.
 domain: cybersecurity
 subdomain: digital-forensics
-tags: [forensics, ransomware, malware-analysis, incident-response, encryption-recovery, evidence-collection]
-version: "1.0"
+tags:
+- forensics
+- ransomware
+- malware-analysis
+- incident-response
+- encryption-recovery
+- evidence-collection
+version: '1.0'
 author: mahipal
 license: Apache-2.0
+nist_csf:
+- RS.AN-01
+- RS.AN-03
+- DE.AE-02
+- RS.MA-01
 ---
 
 # Investigating Ransomware Attack Artifacts