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/testing-websocket-api-security/SKILL.md

@@ -1,11 +1,13 @@
 ---
 name: testing-websocket-api-security
-description: 'Tests WebSocket API implementations for security vulnerabilities including missing authentication on WebSocket
-  upgrade, Cross-Site WebSocket Hijacking (CSWSH), injection attacks through WebSocket messages, insufficient input validation,
-  denial-of-service via message flooding, and information leakage through WebSocket frames. The tester intercepts WebSocket
-  handshakes and messages using Burp Suite, crafts malicious payloads, and tests for authorization bypass on WebSocket channels.
-  Activates for requests involving WebSocket security testing, WS penetration testing, CSWSH attack, or real-time API security
-  assessment.
+description: 'Tests WebSocket API implementations for security vulnerabilities including
+  missing authentication on WebSocket upgrade, Cross-Site WebSocket Hijacking (CSWSH),
+  injection attacks through WebSocket messages, insufficient input validation, denial-of-service
+  via message flooding, and information leakage through WebSocket frames. The tester
+  intercepts WebSocket handshakes and messages using Burp Suite, crafts malicious
+  payloads, and tests for authorization bypass on WebSocket channels. Activates for
+  requests involving WebSocket security testing, WS penetration testing, CSWSH attack,
+  or real-time API security assessment.
 
   '
 domain: cybersecurity
@@ -25,6 +27,12 @@ nist_csf:
 - ID.RA-01
 - PR.DS-10
 - DE.CM-01
+mitre_attack:
+- T1190
+- T1059.007
+- T1552.001
+- T1055
+- T1059
 ---
 # Testing WebSocket API Security