Rewrite 548 skill descriptions to the activation rubric

Each rewritten description now states both what the skill does (concrete
capability, named tools/artifacts) and an explicit when-to-use trigger,
improving agent discovery/activation. Grounded in each skill's own body;
changes confined to the `description` field only (bodies and all other
frontmatter untouched). Produced by a gated audit->rewrite->recheck loop
(548 -> 0 flagged) with a sampled anti-invention check (0 ungrounded).

Schema: 817/817 pass. Framework-ID gate: 0 defects.

skills/implementing-continuous-security-validation-with-bas/SKILL.md

@@ -1,8 +1,10 @@
 ---
 name: implementing-continuous-security-validation-with-bas
-description: Deploy Breach and Attack Simulation tools to continuously validate security
-  control effectiveness by safely emulating real-world attack techniques across the
-  kill chain.
+description: Deploys Breach and Attack Simulation (BAS) platforms such as SafeBreach,
+  AttackIQ, Picus, Cymulate, Pentera, or SCYTHE to continuously validate endpoint,
+  network, email-gateway, SIEM, and incident-response effectiveness by safely emulating
+  MITRE ATT&CK techniques. Use when moving beyond point-in-time pentesting to continuous
+  control validation, or standing up automated adversary emulation.
 domain: cybersecurity
 subdomain: vulnerability-management
 tags: