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/detecting-credential-dumping-techniques/SKILL.md

@@ -1,19 +1,26 @@
 ---
 name: detecting-credential-dumping-techniques
-description: Detect LSASS credential dumping, SAM database extraction, and NTDS.dit theft using Sysmon Event ID 10, Windows Security logs, and SIEM correlation rules
+description: Detect LSASS credential dumping, SAM database extraction, and NTDS.dit theft using Sysmon Event ID 10, Windows
+  Security logs, and SIEM correlation rules
 domain: cybersecurity
 subdomain: threat-detection
 tags:
-  - credential-dumping
-  - lsass
-  - mimikatz
-  - sysmon
-  - active-directory
-  - windows-security
-  - defense-evasion
-version: "1.0"
+- credential-dumping
+- lsass
+- mimikatz
+- sysmon
+- active-directory
+- windows-security
+- defense-evasion
+version: '1.0'
 author: mahipal
 license: Apache-2.0
+d3fend_techniques:
+- Token Binding
+- Execution Isolation
+- File Metadata Consistency Validation
+- Restore Access
+- Application Protocol Command Analysis
 ---
 
 # Detecting Credential Dumping Techniques