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-ssl-stripping-attack/SKILL.md

@@ -1,15 +1,26 @@
 ---
 name: performing-ssl-stripping-attack
-description: >
-  Simulates SSL stripping attacks using sslstrip, Bettercap, and mitmproxy in authorized
-  environments to test HSTS enforcement, certificate validation, and HTTPS upgrade
-  mechanisms that protect users from downgrade attacks on encrypted connections.
+description: 'Simulates SSL stripping attacks using sslstrip, Bettercap, and mitmproxy in authorized environments to test
+  HSTS enforcement, certificate validation, and HTTPS upgrade mechanisms that protect users from downgrade attacks on encrypted
+  connections.
+
+  '
 domain: cybersecurity
 subdomain: network-security
-tags: [network-security, ssl-stripping, https, hsts, tls-security]
-version: "1.0"
+tags:
+- network-security
+- ssl-stripping
+- https
+- hsts
+- tls-security
+version: '1.0'
 author: mahipal
 license: Apache-2.0
+nist_csf:
+- PR.IR-01
+- DE.CM-01
+- ID.AM-03
+- PR.DS-02
 ---
 # Performing SSL Stripping Attack