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-yara-rule-development-for-detection/SKILL.md

@@ -1,12 +1,25 @@
 ---
 name: performing-yara-rule-development-for-detection
-description: Develop precise YARA rules for malware detection by identifying unique byte patterns, strings, and behavioral indicators in executable files while minimizing false positives.
+description: Develop precise YARA rules for malware detection by identifying unique byte patterns, strings, and behavioral
+  indicators in executable files while minimizing false positives.
 domain: cybersecurity
 subdomain: malware-analysis
-tags: [yara, malware-detection, signature-development, threat-hunting, pattern-matching, yara-x, indicator-development]
-version: "1.0"
+tags:
+- yara
+- malware-detection
+- signature-development
+- threat-hunting
+- pattern-matching
+- yara-x
+- indicator-development
+version: '1.0'
 author: mahipal
 license: Apache-2.0
+nist_csf:
+- DE.AE-02
+- RS.AN-03
+- ID.RA-01
+- DE.CM-01
 ---
 # Performing YARA Rule Development for Detection