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/hunting-credential-stuffing-attacks/SKILL.md

@@ -1,16 +1,25 @@
 ---
 name: hunting-credential-stuffing-attacks
-description: >
-  Detects credential stuffing attacks by analyzing authentication logs for login velocity
-  anomalies, ASN diversity, password spray patterns, and geographic distribution of failed
-  logins. Uses statistical analysis on Splunk or raw log data. Use when investigating
-  account takeover campaigns or building detection rules for auth abuse.
+description: 'Detects credential stuffing attacks by analyzing authentication logs for login velocity anomalies, ASN diversity,
+  password spray patterns, and geographic distribution of failed logins. Uses statistical analysis on Splunk or raw log data.
+  Use when investigating account takeover campaigns or building detection rules for auth abuse.
+
+  '
 domain: cybersecurity
 subdomain: security-operations
-tags: [hunting, credential, stuffing, attacks]
-version: "1.0"
+tags:
+- hunting
+- credential
+- stuffing
+- attacks
+version: '1.0'
 author: mahipal
 license: Apache-2.0
+nist_csf:
+- DE.CM-01
+- RS.MA-01
+- GV.OV-01
+- DE.AE-02
 ---
 
 # Hunting Credential Stuffing Attacks