Integrate MAS with Synapse

mas/share/templates/pages/upstream_oauth2/link_mismatch.html

@@ -0,0 +1,25 @@
+{#
+Copyright 2024, 2025 New Vector Ltd.
+Copyright 2022-2024 The Matrix.org Foundation C.I.C.
+
+SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE files in the repository root for full details.
+-#}
+
+{% extends "base.html" %}
+
+{% block content %}
+  <header class="page-heading">
+    <div class="icon invalid">
+      {{ icon.warning() }}
+    </div>
+
+    <div class="header">
+      <h1 class="title">
+        {{ _("mas.upstream_oauth2.link_mismatch.heading") }}
+      </h1>
+    </div>
+  </header>
+
+  {{ logout.button(text=_("action.sign_out"), csrf_token=csrf_token) }}
+{% endblock content %}