feat: web UI on socket protocol 2 (step 2b)

The UI talks to the device over the one socket at /ws: the sync fills the
shade model, its events redraw the lists, and every read, command, edit,
setting, scan and reboot is an op. Only /loginContext, /login and the file
transfers stay on HTTP, so a page load opens no other connection.

- The 8080 socket, editJSON/requestResult and the /controller, /rooms,
  /shades, /groups, /room, /shade, /group, settings and command routes are
  no longer used by the UI.
- An edit's callback gets the item once its event is in (ProtoClient
  waitFor); busy edits and saves are sent again.
- The token is kept in sessionStorage. When /ws is refused and
  /loginContext says a login is needed, the client stops retrying and the
  login panel opens. Backup and uploads send the token.
- A banner shows when the device speaks another protocol version.
- Removed dead code: the /pairShade call and its unused /unpairShade twin,
  loadLogin, login.html (broken, linked from nowhere), Secure Config Only's
  checkbox (protocol 2 has two modes) and the HTTP helpers nothing uses.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

data-src/index.html

@@ -179,10 +179,6 @@
                                 </select>
                                 <label for="fldPinEntry">Security Type</label>
                             </div>
-                            <div id="divPermissions" class="field-group" style="display:none;vertical-align:middle;float:right;width:auto;">
-                                <input id="cbSecureConfigOnly" data-bind="security.permissions.configOnly" type="checkbox" style="display:inline-block;" />
-                                <label for="cbSecureConfigOnly" style="display:inline-block;cursor:pointer;">Secure Config Only</label>
-                            </div>
                         </div>
                         <div id="divPinSecurity" style="display:none;">
                             <div class="field-group" style="text-align:center;">