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/exploiting-http-request-smuggling/SKILL.md

@@ -1,8 +1,12 @@
 ---
 name: exploiting-http-request-smuggling
-description: Detecting and exploiting HTTP request smuggling vulnerabilities caused
-  by Content-Length and Transfer-Encoding parsing discrepancies between front-end
-  and back-end servers.
+description: >-
+  Detects and exploits HTTP request smuggling caused by Content-Length/Transfer-Encoding
+  parsing discrepancies between front-end and back-end servers, using Burp Suite
+  Repeater (auto Content-Length disabled), the HTTP Request Smuggler extension, and
+  smuggler.py. Use during authorized tests of multi-tier architectures behind a
+  reverse proxy, load balancer, or CDN to find desync flaws and bypass front-end
+  controls.
 domain: cybersecurity
 subdomain: web-application-security
 tags: