feat: enrich 209 skills with MITRE ATLAS, D3FEND, and NIST AI RMF frontmatter

Added structured security framework mappings to SKILL.md frontmatter across all applicable skills:
- atlas_techniques: MITRE ATLAS v5.5 AML.TXXXX IDs (81 skills, AI-targeted attack techniques)
- d3fend_techniques: MITRE D3FEND v1.3 defensive technique labels (139 skills, mapped from ATT&CK IDs)
- nist_ai_rmf: NIST AI RMF 1.0 subcategory IDs (85 skills, AI risk management functions)

Also updates ATTACK_COVERAGE.md with coverage statistics for all three frameworks.

skills/implementing-fuzz-testing-in-cicd-with-aflplusplus/SKILL.md

@@ -1,12 +1,28 @@
 ---
 name: implementing-fuzz-testing-in-cicd-with-aflplusplus
-description: Integrate AFL++ coverage-guided fuzz testing into CI/CD pipelines to discover memory corruption, input handling, and logic vulnerabilities in C/C++ and compiled applications.
+description: Integrate AFL++ coverage-guided fuzz testing into CI/CD pipelines to discover memory corruption, input handling,
+  and logic vulnerabilities in C/C++ and compiled applications.
 domain: cybersecurity
 subdomain: devsecops
-tags: [aflplusplus, fuzz-testing, cicd, coverage-guided-fuzzing, security-testing, vulnerability-discovery, afl]
-version: "1.0"
+tags:
+- aflplusplus
+- fuzz-testing
+- cicd
+- coverage-guided-fuzzing
+- security-testing
+- vulnerability-discovery
+- afl
+version: '1.0'
 author: mahipal
 license: Apache-2.0
+nist_ai_rmf:
+- MEASURE-2.7
+- MAP-5.1
+- MANAGE-2.4
+atlas_techniques:
+- AML.T0070
+- AML.T0066
+- AML.T0082
 ---
 
 # Implementing Fuzz Testing in CI/CD with AFL++