Fix security reset UX: full-screen overlay, CSS class bug, and auto-reconnect

- Add security-reset-overlay HTML element to index.html that shows immediately
  when the user confirms "Erase & Reset", before the synchronous API call runs
- Add .security-reset-overlay CSS to security.css (reuses reboot-card styles,
  adds fade-in animation, z-index 1000 to sit above all other content)
- Fix reboot overlay class bug: classList.add("open") → classList.add("visible")
  so the overlay actually renders per the .reboot-overlay.visible CSS rule
- Show overlay step text "Erasing data and resetting credentials…" during wipe,
  update to "Reset complete. Rebooting now…" when API returns
- Call waitForServerReboot() (globally defined in update.js) after reset so the
  page auto-reloads when the system comes back online
- Hide the security-reset-overlay and re-enable the button on error

Agent-Logs-Url: https://github.com/naturallaw777/staging_alpha/sessions/185d0b41-d54d-4ea2-93d6-bfb7c15b8aed

Co-authored-by: naturallaw777 <99053422+naturallaw777@users.noreply.github.com>

app/sovran_systemsos_web/templates/index.html

@@ -210,6 +210,25 @@
     </div>
   </div>
 
+  <!-- Security Reset overlay -->
+  <div class="security-reset-overlay" id="security-reset-overlay">
+    <div class="reboot-card">
+      <div class="security-reset-overlay-icon">🛡</div>
+      <h2 class="reboot-title">Security Reset In Progress</h2>
+      <p class="reboot-message">
+        ⚠️ Wiping all data and credentials.<br />
+        <strong>Do not power off your computer.</strong><br />
+        This may take several minutes. The system will reboot automatically when complete.
+      </p>
+      <div class="reboot-dots">
+        <span class="reboot-dot"></span>
+        <span class="reboot-dot"></span>
+        <span class="reboot-dot"></span>
+      </div>
+      <p class="reboot-submessage" id="security-reset-overlay-step">Erasing data and resetting credentials…</p>
+    </div>
+  </div>
+
   <!-- Reboot overlay -->
   <div class="reboot-overlay" id="reboot-overlay">
     <div class="reboot-card">