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-bgp-security-with-rpki/SKILL.md

@@ -1,8 +1,11 @@
 ---
 name: implementing-bgp-security-with-rpki
-description: Implement BGP route origin validation using RPKI with Route Origin Authorizations,
-  RPKI-to-Router protocol, and ROV policies on Cisco and Juniper routers to prevent
-  route hijacking.
+description: Implement RPKI-based BGP route origin validation by creating Route Origin
+  Authorizations (ROAs) at RIRs (ARIN, RIPE, APNIC, AFRINIC, LACNIC), deploying validator
+  software (Routinator, FORT, OctoRPKI), and configuring RPKI-to-Router protocol and
+  ROV accept/reject policies on Cisco IOS-XE and Juniper Junos routers. Use when hardening
+  BGP against route hijacking or leaks, or when configuring ROV filtering policy on
+  production routers.
 domain: cybersecurity
 subdomain: network-security
 tags: