feat: 新增 Signal 群組連結

- 在 Footer 聯繫區塊新增 Signal 連結
- 在首頁「加入我們」區塊新增 Signal 為主要 CTA
- 新增說明文字「與密碼龐克們一起探索隱私與自由」

Author: awesome-doge

_includes/footer.html

@@ -141,6 +141,14 @@ <h4 class="text-cp-green-500 font-mono font-bold mb-4 text-sm uppercase tracking
             </a>
           </li>
           {% endif %}
+          <li>
+            <a href="https://signal.group/#CjQKIJkrnL-dvsydyzn9Xl4HYZI9-Paf14vYkCq4eh5LhZeyEhALctkOeMMDuSOmYtgvj9QU" target="_blank" rel="noopener noreferrer" class="inline-flex items-center gap-2 text-cp-dark-700 hover:text-cp-green-500 text-sm font-mono transition-colors">
+              <svg class="w-4 h-4" fill="currentColor" viewBox="0 0 24 24">
+                <path d="M12 2C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2zm-1 17.93c-3.95-.49-7-3.85-7-7.93 0-.62.08-1.21.21-1.79L9 15v1c0 1.1.9 2 2 2v1.93zm6.9-2.54c-.26-.81-1-1.39-1.9-1.39h-1v-3c0-.55-.45-1-1-1H8v-2h2c.55 0 1-.45 1-1V7h2c1.1 0 2-.9 2-2v-.41c2.93 1.19 5 4.06 5 7.41 0 2.08-.8 3.97-2.1 5.39z"/>
+              </svg>
+              Signal
+            </a>
+          </li>
         </ul>
       </div>
 

index.html

@@ -429,11 +429,20 @@ <h2 class="text-2xl font-bold font-mono text-cp-green-500 mb-12 text-center scro
 <!-- Social Links Section -->
 <section class="py-20 bg-cp-dark-100 -mx-4 md:-mx-8 px-4 md:px-8">
   <div class="max-w-4xl mx-auto text-center">
-    <h2 class="text-2xl font-bold font-mono text-cp-green-500 mb-12 scroll-reveal">
+    <h2 class="text-2xl font-bold font-mono text-cp-green-500 mb-4 scroll-reveal">
       <span class="text-cp-dark-600">//</span> 加入我們
     </h2>
+    <p class="text-cp-dark-600 font-mono text-sm mb-12 scroll-reveal">與密碼龐克們一起探索隱私與自由</p>
 
     <div class="flex flex-wrap items-center justify-center gap-6 scroll-reveal">
+      <!-- Signal - Primary CTA -->
+      <a href="https://signal.group/#CjQKIJkrnL-dvsydyzn9Xl4HYZI9-Paf14vYkCq4eh5LhZeyEhALctkOeMMDuSOmYtgvj9QU" target="_blank" rel="noopener noreferrer" class="social-btn flex items-center gap-3 px-8 py-4 bg-cp-green-500/10 border-2 border-cp-green-500 rounded-lg hover:bg-cp-green-500/20 text-cp-green-500 transition-all font-mono group">
+        <svg class="w-6 h-6 group-hover:scale-110 transition-transform" fill="currentColor" viewBox="0 0 24 24">
+          <path d="M12 2C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2zm-1 17.93c-3.95-.49-7-3.85-7-7.93 0-.62.08-1.21.21-1.79L9 15v1c0 1.1.9 2 2 2v1.93zm6.9-2.54c-.26-.81-1-1.39-1.9-1.39h-1v-3c0-.55-.45-1-1-1H8v-2h2c.55 0 1-.45 1-1V7h2c1.1 0 2-.9 2-2v-.41c2.93 1.19 5 4.06 5 7.41 0 2.08-.8 3.97-2.1 5.39z"/>
+        </svg>
+        加入 Signal
+      </a>
+
       <a href="https://github.com/cypherpunks-core" target="_blank" rel="noopener noreferrer" class="social-btn flex items-center gap-3 px-8 py-4 bg-cp-dark-200 border border-cp-dark-400 rounded-lg hover:border-cp-green-500 hover:text-cp-green-500 transition-all font-mono group">
         <svg class="w-6 h-6 group-hover:scale-110 transition-transform" fill="currentColor" viewBox="0 0 24 24">
           <path fill-rule="evenodd" clip-rule="evenodd" d="M12 2C6.477 2 2 6.477 2 12c0 4.42 2.865 8.17 6.839 9.49.5.092.682-.217.682-.482 0-.237-.008-.866-.013-1.7-2.782.604-3.369-1.34-3.369-1.34-.454-1.156-1.11-1.464-1.11-1.464-.908-.62.069-.608.069-.608 1.003.07 1.531 1.03 1.531 1.03.892 1.529 2.341 1.087 2.91.831.092-.646.35-1.086.636-1.336-2.22-.253-4.555-1.11-4.555-4.943 0-1.091.39-1.984 1.029-2.683-.103-.253-.446-1.27.098-2.647 0 0 .84-.269 2.75 1.025A9.578 9.578 0 0112 6.836c.85.004 1.705.114 2.504.336 1.909-1.294 2.747-1.025 2.747-1.025.546 1.377.203 2.394.1 2.647.64.699 1.028 1.592 1.028 2.683 0 3.842-2.339 4.687-4.566 4.935.359.309.678.919.678 1.852 0 1.336-.012 2.415-.012 2.743 0 .267.18.578.688.48C19.138 20.167 22 16.418 22 12c0-5.523-4.477-10-10-10z"/>