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/exploiting-jwt-algorithm-confusion-attack/SKILL.md

@@ -1,10 +1,12 @@
 ---
 name: exploiting-jwt-algorithm-confusion-attack
-description: 'Exploits JWT algorithm confusion vulnerabilities where the server''s token verification library accepts the
-  algorithm specified in the JWT header rather than enforcing a fixed algorithm. The tester manipulates the alg header to
-  switch from RS256 to HS256 (using the RSA public key as the HMAC secret), sets alg to none to bypass signature verification,
-  or exploits kid/jku/x5u header injection to supply attacker-controlled keys. Activates for requests involving JWT algorithm
-  confusion, alg none attack, key confusion attack, or JWT signature bypass.
+description: 'Exploits JWT algorithm confusion vulnerabilities where the server''s
+  token verification library accepts the algorithm specified in the JWT header rather
+  than enforcing a fixed algorithm. The tester manipulates the alg header to switch
+  from RS256 to HS256 (using the RSA public key as the HMAC secret), sets alg to none
+  to bypass signature verification, or exploits kid/jku/x5u header injection to supply
+  attacker-controlled keys. Activates for requests involving JWT algorithm confusion,
+  alg none attack, key confusion attack, or JWT signature bypass.
 
   '
 domain: cybersecurity
@@ -23,6 +25,12 @@ nist_csf:
 - ID.RA-01
 - PR.DS-10
 - DE.CM-01
+mitre_attack:
+- T1190
+- T1059.007
+- T1552.001
+- T1055
+- T1059
 ---
 # Exploiting JWT Algorithm Confusion Attack