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/performing-vlan-hopping-attack/SKILL.md

@@ -1,15 +1,25 @@
 ---
 name: performing-vlan-hopping-attack
-description: >
-  Simulates VLAN hopping attacks using switch spoofing and double tagging techniques
-  in authorized environments to test VLAN segmentation effectiveness and validate
-  switch port security configurations against Layer 2 bypass attacks.
+description: 'Simulates VLAN hopping attacks using switch spoofing and double tagging techniques in authorized environments
+  to test VLAN segmentation effectiveness and validate switch port security configurations against Layer 2 bypass attacks.
+
+  '
 domain: cybersecurity
 subdomain: network-security
-tags: [network-security, vlan-hopping, layer2-attack, switch-security, 802.1q]
-version: "1.0"
+tags:
+- network-security
+- vlan-hopping
+- layer2-attack
+- switch-security
+- 802.1q
+version: '1.0'
 author: mahipal
 license: Apache-2.0
+nist_csf:
+- PR.IR-01
+- DE.CM-01
+- ID.AM-03
+- PR.DS-02
 ---
 # Performing VLAN Hopping Attack