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-gdpr-data-protection-controls/SKILL.md

@@ -12,14 +12,11 @@ tags:
 - data-protection
 - eu-regulation
 nist_csf:
-- GV.OC
-- GV.PO
-- GV.RR
-- ID.AM
-- PR.AA
-- PR.DS
-- RS.CO
-- RS.MA
+- GV.OC-02
+- GV.PO-01
+- PR.DS-01
+- PR.AA-01
+- ID.AM-02
 version: '1.0'
 author: mahipal
 license: Apache-2.0