Descriptions are inline markdown; Feature.link withdrawn

Alternative and feature descriptions render links, emphasis and code
(pulldown-cmark, html feature only). Block structure flattens to one
paragraph, raw HTML is dropped, link targets are limited to https,
mailto and site-relative paths. A link belongs in the prose, so the
title-link field shipped in 0.3.7 goes before anyone uses it.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

style/main.css

@@ -448,15 +448,22 @@ main.not-found {
   margin-bottom: 0.15em;
 }
 
-.feature h3 a {
+/* links inside markdown descriptions */
+.alt-description a,
+.feature p a {
   color: inherit;
   text-decoration: none;
-  border-bottom: 0.06rem solid var(--line);
+  border-bottom: 0.06rem solid var(--accent);
 }
 
-.feature h3 a:hover {
+.alt-description a:hover,
+.feature p a:hover {
   color: var(--accent);
-  border-bottom-color: var(--accent);
+}
+
+.alt-description code,
+.feature p code {
+  font-size: 0.9em;
 }
 
 .feature p {