Map all 754 skills to MITRE ATT&CK v19.1

- Add validated mitre_attack frontmatter to all 754 skills (286 distinct
  techniques), verified against MITRE ATT&CK v19.1 via the official
  mitreattack-python library: 0 revoked, deprecated, or invalid IDs
- Curate precise per-skill technique IDs for forensics, malware-analysis,
  threat-intel, and red-team skills (e.g. DCSync -> T1003.006,
  Kerberoasting -> T1558.003, Pass-the-Ticket -> T1550.003)
- Reconcile v19.1 tactic restructuring: Defense Evasion split into
  Stealth (TA0005) and Defense Impairment (TA0112); revoked T1562.*
  family and T1070.001/.002 remapped to active equivalents (T1685.*)
- Normalize word-split tags across 35 skills (remove filename-derived
  stopword tags, add semantic cybersecurity tags)
- Add api-reference.md for 3 skills that were missing it
- Update README ATT&CK section with accurate v19.1 tactic distribution

skills/configuring-active-directory-tiered-model/SKILL.md

@@ -1,7 +1,8 @@
 ---
 name: configuring-active-directory-tiered-model
-description: Implement Microsoft's Enhanced Security Admin Environment (ESAE) tiered administration model for Active Directory.
-  Covers Tier 0/1/2 separation, privileged access workstations (PAWs), administrative f
+description: Implement Microsoft's Enhanced Security Admin Environment (ESAE) tiered
+  administration model for Active Directory. Covers Tier 0/1/2 separation, privileged
+  access workstations (PAWs), administrative f
 domain: cybersecurity
 subdomain: identity-access-management
 tags:
@@ -20,6 +21,12 @@ nist_csf:
 - PR.AA-02
 - PR.AA-05
 - PR.AA-06
+mitre_attack:
+- T1078.002
+- T1550.002
+- T1550.003
+- T1003.001
+- T1021
 ---
 # Configuring Active Directory Tiered Model