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/implementing-microsegmentation-with-guardicore/SKILL.md

@@ -1,8 +1,9 @@
 ---
 name: implementing-microsegmentation-with-guardicore
-description: 'Implementing microsegmentation using Akamai Guardicore Segmentation to map application dependencies, create
-  granular network policies, visualize east-west traffic flows, and enforce least-privilege communication between workloads
-  across data centers and cloud.
+description: 'Implementing microsegmentation using Akamai Guardicore Segmentation
+  to map application dependencies, create granular network policies, visualize east-west
+  traffic flows, and enforce least-privilege communication between workloads across
+  data centers and cloud.
 
   '
 domain: cybersecurity
@@ -23,6 +24,12 @@ nist_csf:
 - PR.AA-05
 - PR.IR-01
 - GV.PO-01
+mitre_attack:
+- T1078
+- T1190
+- T1059
+- T1021
+- T1550
 ---
 
 # Implementing Microsegmentation with Guardicore