add hide-elevate-button-in-accept-window (#16271)

A portable client handed to standard users offers them "Accept and Elevate",
which they have no credentials to complete. The builtin option takes that
button out of the accept window and leaves elevation to the controlling
side's "Request Elevation" during the session.

https://github.com/rustdesk/rustdesk-server-pro/discussions/1016


Claude-Session: https://claude.ai/code/session_01EZ49AbZJYfm8NTp5yDPMab

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

flutter/lib/consts.dart

@@ -126,6 +126,8 @@ const String kOptionEnableBlockInput = "enable-block-input";
 const String kOptionEnablePrivacyMode = "enable-privacy-mode";
 const String kOptionEnablePermChangeInAcceptWindow =
     "enable-perm-change-in-accept-window";
+const String kOptionHideElevateButtonInAcceptWindow =
+    "hide-elevate-button-in-accept-window";
 const String kOptionAllowRemoteConfigModification =
     "allow-remote-config-modification";
 const String kOptionVerificationMethod = "verification-method";

flutter/lib/desktop/pages/server_page.dart

@@ -1073,7 +1073,10 @@ class _CmControlPanel extends StatelessWidget {
     final model = Provider.of<ServerModel>(context);
     final showElevation = canElevate &&
         model.showElevation &&
-        client.type_() == ClientType.remote;
+        client.type_() == ClientType.remote &&
+        bind.mainGetBuildinOption(
+                key: kOptionHideElevateButtonInAcceptWindow) !=
+            'Y';
     final showAccept = model.approveMode != 'password';
     return Column(
       mainAxisAlignment: MainAxisAlignment.end,