feat: move footer privacy note behind PRIVACY overlay button

DeepDrftPublic.Client/Layout/DeepDrftFooter.razor

@@ -4,8 +4,34 @@
         <ul class="deepdrft-footer-links">
             <li><a href="/about">About</a></li>
             <li><a href="#">Contact</a></li>
+            <li><button class="deepdrft-footer-privacy-btn" @onclick="@OpenPrivacy" type="button" aria-haspopup="dialog">Privacy</button></li>
         </ul>
         <div class="deepdrft-footer-copy">© 2026 Deep DRFT</div>
     </div>
-    <p class="deepdrft-footer-privacy">We keep a random tag in your browser so we can count how many people a track reaches — not who they are. No account, no name, nothing personal, nothing shared with anyone else. Clear your browser data and the tag&#8217;s gone.</p>
-</footer>
+</footer>
+
+<MudOverlay Visible="@_privacyOpen"
+            DarkBackground="true"
+            Modal="true"
+            OnClick="@ClosePrivacy"
+            Class="deepdrft-privacy-overlay">
+    <div class="deepdrft-privacy-modal" @onclick:stopPropagation="true">
+        <div class="deepdrft-privacy-modal-header">
+            <span class="deepdrft-privacy-modal-title">Privacy</span>
+            <MudIconButton Icon="@Icons.Material.Filled.Close"
+                           Size="Size.Small"
+                           Color="Color.Default"
+                           OnClick="@ClosePrivacy"
+                           aria-label="Close privacy note"
+                           Class="deepdrft-privacy-modal-close" />
+        </div>
+        <p class="deepdrft-privacy-modal-body">We keep a random tag in your browser so we can count how many people a track reaches — not who they are. No account, no name, nothing personal, nothing shared with anyone else. Clear your browser data and the tag&#8217;s gone.</p>
+    </div>
+</MudOverlay>
+
+@code {
+    private bool _privacyOpen;
+
+    private void OpenPrivacy() => _privacyOpen = true;
+    private void ClosePrivacy() => _privacyOpen = false;
+}