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-epss-score-for-vulnerability-prioritization/SKILL.md

@@ -1,12 +1,25 @@
 ---
 name: implementing-epss-score-for-vulnerability-prioritization
-description: Integrate FIRST's Exploit Prediction Scoring System (EPSS) API to prioritize vulnerability remediation based on real-world exploitation probability within 30 days.
+description: Integrate FIRST's Exploit Prediction Scoring System (EPSS) API to prioritize vulnerability remediation based
+  on real-world exploitation probability within 30 days.
 domain: cybersecurity
 subdomain: vulnerability-management
-tags: [epss, vulnerability-prioritization, first, exploit-prediction, cvss, risk-based, machine-learning]
-version: "1.0"
+tags:
+- epss
+- vulnerability-prioritization
+- first
+- exploit-prediction
+- cvss
+- risk-based
+- machine-learning
+version: '1.0'
 author: mahipal
 license: Apache-2.0
+nist_csf:
+- ID.RA-01
+- ID.RA-02
+- ID.IM-02
+- ID.RA-06
 ---
 
 # Implementing EPSS Score for Vulnerability Prioritization