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/profiling-threat-actor-groups/SKILL.md

@@ -1,10 +1,12 @@
 ---
 name: profiling-threat-actor-groups
-description: 'Develops comprehensive threat actor profiles for APT groups, criminal organizations, and hacktivist collectives
-  by aggregating TTP documentation, historical campaign data, tooling fingerprints, and attribution indicators from multiple
-  intelligence sources. Use when briefing executives on sector-specific threats, updating threat model assumptions, or prioritizing
-  defensive controls against specific adversaries. Activates for requests involving MITRE ATT&CK Groups, Mandiant APT profiles,
-  CrowdStrike adversary naming, or sector-specific threat briefings.
+description: 'Develops comprehensive threat actor profiles for APT groups, criminal
+  organizations, and hacktivist collectives by aggregating TTP documentation, historical
+  campaign data, tooling fingerprints, and attribution indicators from multiple intelligence
+  sources. Use when briefing executives on sector-specific threats, updating threat
+  model assumptions, or prioritizing defensive controls against specific adversaries.
+  Activates for requests involving MITRE ATT&CK Groups, Mandiant APT profiles, CrowdStrike
+  adversary naming, or sector-specific threat briefings.
 
   '
 domain: cybersecurity
@@ -26,6 +28,12 @@ nist_csf:
 - ID.RA-05
 - DE.CM-01
 - DE.AE-02
+mitre_attack:
+- T1591
+- T1592
+- T1593
+- T1589
+- T1566
 ---
 # Profiling Threat Actor Groups