feat: complete UI redesign — modern, clean search interface

- New CSS: complete design system with CSS variables, modern color palette
- Homepage: full-viewport hero with centered search, logo, tagline
- Result cards: rounded, shadowed, with favicons via Google Favicon API
- Layout: sidebar + results grid, responsive
- Typography: proper font stack, variable weights
- Settings panel: polished popover with animations
- Autocomplete: modern dropdown with keyboard nav
- Dark mode: full color palette via data-theme attribute
- Favicon: clean search icon SVG

internal/views/templates/index.html

@@ -1,15 +1,23 @@
 {{define "title"}}{{end}}
 {{define "content"}}
-<div class="index">
-  <div class="title"><h1>kafka</h1></div>
-  <div id="search">
+<div class="search-hero">
+  <div class="hero-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…" autocomplete="off" autofocus
-        hx-get="/search" hx-target="#results" hx-trigger="keyup changed delay:500ms" hx-include="this">
-      <button type="submit">Search</button>
-      <input type="hidden" name="engines" id="engines-input" value="">
+      <input type="text" name="q" id="q" placeholder="Search the web…" autocomplete="off" autofocus>
+      <button type="submit" class="search-box-submit" 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 id="autocomplete-dropdown"></div>
   </div>
 </div>
 <div id="results"></div>