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-user-behavior-analytics/SKILL.md

@@ -1,16 +1,29 @@
 ---
 name: performing-user-behavior-analytics
-description: >
-  Performs User and Entity Behavior Analytics (UEBA) to detect anomalous user activities including
-  impossible travel, unusual access patterns, privilege abuse, and insider threats using SIEM-based
-  behavioral baselines and statistical analysis. Use when SOC teams need to identify compromised
-  accounts or insider threats through deviation from established behavioral norms.
+description: 'Performs User and Entity Behavior Analytics (UEBA) to detect anomalous user activities including impossible
+  travel, unusual access patterns, privilege abuse, and insider threats using SIEM-based behavioral baselines and statistical
+  analysis. Use when SOC teams need to identify compromised accounts or insider threats through deviation from established
+  behavioral norms.
+
+  '
 domain: cybersecurity
 subdomain: soc-operations
-tags: [soc, ueba, user-behavior, insider-threat, anomaly-detection, splunk, baseline]
-version: "1.0"
+tags:
+- soc
+- ueba
+- user-behavior
+- insider-threat
+- anomaly-detection
+- splunk
+- baseline
+version: '1.0'
 author: mahipal
 license: Apache-2.0
+nist_csf:
+- DE.CM-01
+- DE.AE-02
+- RS.MA-01
+- DE.AE-06
 ---
 # Performing User Behavior Analytics