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-ssrf-vulnerability-exploitation/SKILL.md

@@ -1,16 +1,23 @@
 ---
 name: performing-ssrf-vulnerability-exploitation
-description: >-
-  Test for Server-Side Request Forgery vulnerabilities by probing cloud metadata endpoints,
-  internal network services, and protocol handlers through user-controllable URL parameters.
-  Tests AWS/GCP/Azure metadata APIs (169.254.169.254), internal port scanning via HTTP,
-  URL scheme bypass techniques, and DNS rebinding detection.
+description: Test for Server-Side Request Forgery vulnerabilities by probing cloud metadata endpoints, internal network services,
+  and protocol handlers through user-controllable URL parameters. Tests AWS/GCP/Azure metadata APIs (169.254.169.254), internal
+  port scanning via HTTP, URL scheme bypass techniques, and DNS rebinding detection.
 domain: cybersecurity
 subdomain: security-operations
-tags: [performing, ssrf, vulnerability, exploitation]
-version: "1.0"
+tags:
+- performing
+- ssrf
+- vulnerability
+- exploitation
+version: '1.0'
 author: mahipal
 license: Apache-2.0
+nist_csf:
+- DE.CM-01
+- RS.MA-01
+- GV.OV-01
+- DE.AE-02
 ---