Add user menu that is opened via right-clicking/long-tapped on avatar

We can un-clutter our message context menu, which we had to share
with user actions. (Even though we only had one so far.) I added one new
user-specific action which allows you to quickly mention the user in
chat. Otherwise you would've had to copy their username or use the
completion menu.

It's convergent on mobile, it still has the hover indicator and it also
is available through the AuthorComponent.

BUG: 486252

src/app/CMakeLists.txt

@@ -101,6 +101,7 @@ ecm_add_qml_module(neochat URI org.kde.neochat GENERATE_PLUGIN_SOURCE
         qml/AvatarNotification.qml
         qml/ReasonDialog.qml
         qml/NewPollDialog.qml
+        qml/UserMenu.qml
     DEPENDENCIES
         QtCore
         QtQuick

src/app/qml/UserMenu.qml

@@ -0,0 +1,35 @@
+// SPDX-FileCopyrightText: 2025 Joshua Goins <josh@redstrate.com>
+// SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
+
+import QtQuick
+import QtQuick.Controls as QQC2
+import QtQuick.Layouts
+
+import org.kde.kirigami as Kirigami
+import org.kde.kirigamiaddons.components as KirigamiComponents
+
+import org.kde.neochat
+import org.kde.neochat.settings
+import org.kde.neochat.devtools
+
+KirigamiComponents.ConvergentContextMenu {
+    id: root
+
+    required property NeoChatConnection connection
+    required property Kirigami.ApplicationWindow window
+    required property var author
+
+    QQC2.Action {
+        text: i18nc("@action:button", "Open Profile")
+        icon.name: "im-user-symbolic"
+        onTriggered: RoomManager.resolveResource(root.author.uri)
+    }
+
+    QQC2.Action {
+        text: i18nc("@action:button", "Mention")
+        icon.name: "username-copy-symbolic"
+        onTriggered: {
+            RoomManager.currentRoom.mainCache.mentionAdded(root.author.id);
+        }
+    }
+}