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-pass-the-hash-attacks/SKILL.md

@@ -1,12 +1,25 @@
 ---
 name: detecting-pass-the-hash-attacks
-description: Detect Pass-the-Hash attacks by analyzing NTLM authentication patterns, identifying Type 3 logons with NTLM where Kerberos is expected, and correlating with credential dumping.
+description: Detect Pass-the-Hash attacks by analyzing NTLM authentication patterns, identifying Type 3 logons with NTLM where
+  Kerberos is expected, and correlating with credential dumping.
 domain: cybersecurity
 subdomain: threat-hunting
-tags: [threat-hunting, mitre-attack, pass-the-hash, credential-access, t1550, proactive-detection]
-version: "1.0"
+tags:
+- threat-hunting
+- mitre-attack
+- pass-the-hash
+- credential-access
+- t1550
+- proactive-detection
+version: '1.0'
 author: mahipal
 license: Apache-2.0
+d3fend_techniques:
+- Token Binding
+- Execution Isolation
+- Restore Access
+- Application Protocol Command Analysis
+- Process Termination
 ---
 
 # Detecting Pass The Hash Attacks