feat(ui): optional UI_HIDE_* panels; doc WARP free vs paid plans

Hide users/warp/cascade blocks via env; block warp/cascade APIs when hidden.
install.sh passes UI_HIDE_* and restores from previous container on upgrade.

Co-authored-by: Cursor <cursoragent@cursor.com>

public/index.html

@@ -135,9 +135,7 @@
       </form>
     </section>
 
-    <section class="panel">
-      <div class="panel-head">
-        <h2>Пользователи</h2>
+    <section class="panel" id="users-panel">
         <span class="muted" id="peer-count"></span>
       </div>
       <div class="table-wrap">
@@ -156,8 +154,7 @@
       </div>
     </section>
 
-    <details class="raw">
-      <summary>Вывод awg show (отладка)</summary>
+    <details class="raw" id="wg-raw-details">
       <pre id="wg-show"></pre>
     </details>
   </div>