refactor(frontend): port search-zen-50 style to Go templates

Replace React SPA with simple Go templates using search-zen-50
visual style. No JavaScript required - pure HTML/CSS with clean
teal accent color scheme, monospace logo, and minimal design.

- Simplified base.html without HTMX or autocomplete JS
- Clean homepage with centered search box
- Results page with sticky header and category tabs
- Simplified CSS matching search-zen-50 aesthetics

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/views/templates/index.html

@@ -1,60 +1,25 @@
 {{define "title"}}{{end}}
 {{define "content"}}
-<div class="search-hero">
-  <div class="hero-logo">
+<div class="home-container">
+  <a href="/" class="home-logo">
     <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true">
       <circle cx="11" cy="11" r="8"/>
       <path d="m21 21-4.35-4.35"/>
     </svg>
-  </div>
-  <p class="hero-tagline">Search the web privately, without tracking or censorship.</p>
-  <div class="search-box">
-    <form method="GET" action="/search" role="search" id="search-form">
-      <input type="text" name="q" id="q" placeholder="Search the web…" autocomplete="off" autofocus>
-      <button type="submit" class="search-box-submit" aria-label="Search">
+    <span class="home-logo-text">kafka</span>
+  </a>
+  <p class="home-tagline">Private meta-search, powered by open source.</p>
+
+  <form class="search-form" method="GET" action="/search" role="search">
+    <div class="search-box">
+      <input type="text" name="q" placeholder="Search the web…" autocomplete="off" autofocus>
+      <button type="submit" class="search-btn" aria-label="Search">
         <svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round">
           <circle cx="11" cy="11" r="8"/>
           <path d="m21 21-4.35-4.35"/>
         </svg>
       </button>
-    </form>
-  </div>
-
-  <!-- Category Tiles -->
-  <div class="category-tiles">
-    <a href="/search" class="category-tile">
-      <span class="category-tile-icon">🌐</span>
-      <span>All</span>
-    </a>
-    <a href="/search?category=images" class="category-tile">
-      <span class="category-tile-icon">🖼️</span>
-      <span>Images</span>
-    </a>
-    <a href="/search?category=news" class="category-tile">
-      <span class="category-tile-icon">📰</span>
-      <span>News</span>
-    </a>
-    <a href="/search?category=videos" class="category-tile">
-      <span class="category-tile-icon">🎬</span>
-      <span>Videos</span>
-    </a>
-    <a href="/search?category=maps" class="category-tile">
-      <span class="category-tile-icon">🗺️</span>
-      <span>Maps</span>
-    </a>
-    <a href="/search?category=shopping" class="category-tile disabled" title="Coming soon">
-      <span class="category-tile-icon">🛒</span>
-      <span>Shopping</span>
-    </a>
-    <a href="/search?category=music" class="category-tile disabled" title="Coming soon">
-      <span class="category-tile-icon">🎵</span>
-      <span>Music</span>
-    </a>
-    <a href="/search?category=weather" class="category-tile disabled" title="Coming soon">
-      <span class="category-tile-icon">🌤️</span>
-      <span>Weather</span>
-    </a>
-  </div>
+    </div>
+  </form>
 </div>
-<div id="results"></div>
-{{end}}
+{{end}}