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/analyzing-android-malware-with-apktool/SKILL.md

@@ -1,7 +1,8 @@
 ---
 name: analyzing-android-malware-with-apktool
-description: Perform static analysis of Android APK malware samples using apktool for decompilation, jadx for Java source
-  recovery, and androguard for permission analysis, manifest inspection, and suspicious API call detection.
+description: Perform static analysis of Android APK malware samples using apktool
+  for decompilation, jadx for Java source recovery, and androguard for permission
+  analysis, manifest inspection, and suspicious API call detection.
 domain: cybersecurity
 subdomain: malware-analysis
 tags:
@@ -21,6 +22,12 @@ nist_csf:
 - RS.AN-03
 - ID.RA-01
 - DE.CM-01
+mitre_attack:
+- T1406
+- T1407
+- T1626.001
+- T1655.001
+- T1521.001
 ---
 
 # Analyzing Android Malware with Apktool