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-linux-kernel-rootkits/SKILL.md

@@ -1,8 +1,9 @@
 ---
 name: analyzing-linux-kernel-rootkits
-description: Detect kernel-level rootkits in Linux memory dumps using Volatility3 linux plugins (check_syscall, lsmod, hidden_modules),
-  rkhunter system scanning, and /proc vs /sys discrepancy analysis to identify hooked syscalls, hidden kernel modules, and
-  tampered system structures.
+description: Detect kernel-level rootkits in Linux memory dumps using Volatility3
+  linux plugins (check_syscall, lsmod, hidden_modules), rkhunter system scanning,
+  and /proc vs /sys discrepancy analysis to identify hooked syscalls, hidden kernel
+  modules, and tampered system structures.
 domain: cybersecurity
 subdomain: digital-forensics
 tags:
@@ -22,6 +23,10 @@ nist_csf:
 - RS.AN-03
 - DE.AE-02
 - RS.MA-01
+mitre_attack:
+- T1014
+- T1547.006
+- T1564.001
 ---
 
 # Analyzing Linux Kernel Rootkits