site: visible RSS pill on category and tag pages

Autodiscovery alone is invisible since browsers dropped feed-detection
UI — add a small RSS pill in the subheader (new feedHref prop on
BaseLayout) linking to the page's scoped feed.

Claude-Session: https://claude.ai/code/session_01WZaczDJjL3xZ3u5spsN5AL

src/layouts/BaseLayout.astro

@@ -22,6 +22,8 @@ interface Props {
   jsonLd?: Record<string, unknown> | Record<string, unknown>[];
   /** Page-scoped feeds (category/tag) advertised alongside the site-wide ones. */
   feeds?: Array<{ title: string; href: string }>;
+  /** Visible RSS pill in the subheader pointing at this page's scoped feed. */
+  feedHref?: string;
   /** Opt into the wider content tier on roomy viewports (grid/listing pages). */
   wide?: boolean;
 }
@@ -43,6 +45,7 @@ const {
   articleTags,
   jsonLd,
   feeds,
+  feedHref,
   wide,
 } = Astro.props;
 const siteName = 'Unique';
@@ -113,6 +116,11 @@ const year = new Date().getFullYear();
               Updated <time datetime={updatedDate.toISOString()}>{fmtLong.format(updatedDate)}</time>
             </p>
           )}
+          {feedHref && (
+            <p class="subheader-feed">
+              <a href={feedHref}>RSS</a>
+            </p>
+          )}
         </div>
       )}
     </header>
@@ -305,6 +313,23 @@ const year = new Date().getFullYear();
         letter-spacing: 0.08em;
         color: var(--muted);
       }
+      .subheader-feed { margin: 0.45rem 0 0; }
+      .subheader-feed a {
+        display: inline-block;
+        padding: 0.05rem 0.5rem;
+        font-family: ui-sans-serif, system-ui, -apple-system, 'Helvetica Neue', sans-serif;
+        font-size: 0.66rem;
+        font-weight: 600;
+        letter-spacing: 0.04em;
+        text-transform: uppercase;
+        background: var(--rule);
+        color: var(--muted);
+        border-radius: 999px;
+      }
+      .subheader-feed a:hover {
+        color: var(--accent);
+        text-decoration: none;
+      }
 
       @media (max-width: 640px) {
         .masthead-row {