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/implementing-semgrep-for-custom-sast-rules/SKILL.md

@@ -1,12 +1,24 @@
 ---
 name: implementing-semgrep-for-custom-sast-rules
-description: Write custom Semgrep SAST rules in YAML to detect application-specific vulnerabilities, enforce coding standards, and integrate into CI/CD pipelines.
+description: Write custom Semgrep SAST rules in YAML to detect application-specific vulnerabilities, enforce coding standards,
+  and integrate into CI/CD pipelines.
 domain: cybersecurity
 subdomain: devsecops
-tags: [semgrep, sast, static-analysis, custom-rules, devsecops, code-security]
-version: "1.0"
+tags:
+- semgrep
+- sast
+- static-analysis
+- custom-rules
+- devsecops
+- code-security
+version: '1.0'
 author: mahipal
 license: Apache-2.0
+nist_csf:
+- PR.PS-01
+- GV.SC-07
+- ID.IM-04
+- PR.PS-04
 ---
 
 # Implementing Semgrep for Custom SAST Rules