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/detecting-s3-data-exfiltration-attempts/SKILL.md

@@ -1,15 +1,28 @@
 ---
 name: detecting-s3-data-exfiltration-attempts
-description: >
-  Detecting data exfiltration attempts from AWS S3 buckets by analyzing CloudTrail S3
-  data events, VPC Flow Logs, GuardDuty findings, Amazon Macie alerts, and S3 access
-  patterns to identify unauthorized bulk downloads and cross-account data transfers.
+description: 'Detecting data exfiltration attempts from AWS S3 buckets by analyzing CloudTrail S3 data events, VPC Flow Logs,
+  GuardDuty findings, Amazon Macie alerts, and S3 access patterns to identify unauthorized bulk downloads and cross-account
+  data transfers.
+
+  '
 domain: cybersecurity
 subdomain: cloud-security
-tags: [cloud-security, aws, s3, data-exfiltration, guardduty, macie, threat-detection]
-version: "1.0"
+tags:
+- cloud-security
+- aws
+- s3
+- data-exfiltration
+- guardduty
+- macie
+- threat-detection
+version: '1.0'
 author: mahipal
 license: Apache-2.0
+nist_csf:
+- PR.IR-01
+- ID.AM-08
+- GV.SC-06
+- DE.CM-01
 ---
 
 # Detecting S3 Data Exfiltration Attempts