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/detecting-secure-boot-bypass/SKILL.md

@@ -1,6 +1,11 @@
 ---
 name: detecting-secure-boot-bypass
-description: Detect bootkits such as BlackLotus and Bootkitty and Secure Boot bypass via DBX and binary checks.
+description: Detect UEFI Secure Boot bypasses and bootkits such as BlackLotus and
+  Bootkitty by verifying Secure Boot state, checking dbx revocation currency, and
+  hashing EFI boot binaries against known-bad sets using mokutil, efi-readvar/dbxtool,
+  CHIPSEC, sbverify/pesign, and Windows Confirm-SecureBootUEFI. Use when auditing
+  fleet dbx rollout after a bootkit advisory or hunting for pre-OS persistence on
+  a suspected-compromised endpoint.
 domain: cybersecurity
 subdomain: hardware-firmware-security
 tags: