add Google site-search input to header nav

Slim pill-shaped search input. Submits site:qipaobuzz.com queries
to Google in a new tab. Vermilion focus ring matches the Chinese
magazine palette.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/layouts/Layout.astro

@@ -147,6 +147,27 @@ const ads = site.ads;
     }
     nav.nav a:hover { color: var(--accent); }
 
+    /* Site search — slim Google-redirect input, Chinese magazine palette */
+    .site-search { display: inline-flex; }
+    .site-search input {
+      background: var(--bg-card);
+      border: 1px solid var(--line);
+      color: var(--ink);
+      font-family: inherit;
+      font-size: 13px;
+      padding: 6px 14px;
+      border-radius: 999px;
+      width: 150px;
+      transition: width 0.2s ease, border-color 0.15s, box-shadow 0.15s;
+    }
+    .site-search input::placeholder { color: var(--ink-muted); }
+    .site-search input:focus {
+      outline: none;
+      width: 200px;
+      border-color: var(--accent);
+      box-shadow: 0 0 0 3px var(--accent-soft);
+    }
+
     main { padding: 0 0 64px; }
 
     /* ========== Index post cards ========== */
@@ -700,6 +721,10 @@ const ads = site.ads;
           <a href="/">Home</a>
           <a href="/about/">About</a>
           <a href="/rss.xml">RSS</a>
+          <form class="site-search" role="search"
+                onsubmit="event.preventDefault();window.open('https://www.google.com/search?q='+encodeURIComponent('site:qipaobuzz.com '+this.q.value),'_blank');this.q.value='';">
+            <input type="search" name="q" placeholder="Search…" aria-label="Search qipaobuzz" required />
+          </form>
         </nav>
       </div>
     </header>