fix: navigation blink root-caused — defer search-client.js (was parser-blocking mid-body), npm run demo serves the production build through the tunnel; DESIGN.md documents the VT removal + font-swap decision

src/layouts/Base.astro

@@ -107,8 +107,13 @@ const links = [
         </details>
       </div>
     </header>
-    <script is:inline src="/search-client.js"></script>
-    <script is:inline>
+    {/* Search enhancement is deferred — a synchronous script here would stall
+        the parser mid-body on every navigation (blank below the header until
+        it arrives). `defer` + the inline `type="module"` init join the same
+        after-parse in-order queue (HTML spec), so newsSearch is defined first.
+        The forms are plain GET /search, so nothing user-facing waits on JS. */}
+    <script is:inline src="/search-client.js" defer></script>
+    <script is:inline type="module">
       // Header search suggestions (desktop field + mobile reveal); the forms
       // are plain GET /search, so everything below is progressive enhancement.
       newsSearch({ input: 'hdr-q', list: 'hdr-suggest', status: 'hdr-suggest-status', limit: 6, unit: 'suggestion', dismiss: true });