Thread fetch more button

Changes threads so there is a button to fetch more events. Also adds a separator between the thread root and the rest of the events.

src/timeline/FetchButtonComponent.qml

@@ -0,0 +1,52 @@
+// SPDX-FileCopyrightText: 2025 James Graham <james.h.graham@protonmail.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.delegates as Delegates
+
+import org.kde.neochat
+import org.kde.neochat.chatbar
+
+/**
+ * @brief A component to show a reply button for threads in a message bubble.
+ */
+Delegates.RoundedItemDelegate {
+    id: root
+
+    /**
+     * @brief The maximum width that the bubble's content can be.
+     */
+    property real maxContentWidth: -1
+
+    /**
+     * @brief Request more events in the thread be loaded.
+     */
+    signal fetchMoreEvents()
+
+    Layout.fillWidth: true
+    Layout.maximumWidth: root.maxContentWidth
+
+    leftInset: 0
+    rightInset: 0
+
+    highlighted: true
+
+    icon.name: "arrow-up"
+    icon.width: Kirigami.Units.iconSizes.sizeForLabels
+    icon.height: Kirigami.Units.iconSizes.sizeForLabels
+    text: i18nc("@action:button", "Fetch More Events")
+
+    onClicked: {
+        root.fetchMoreEvents()
+    }
+
+    contentItem: Kirigami.Icon {
+        implicitWidth: root.icon.width
+        implicitHeight: root.icon.height
+        source: root.icon.name
+    }
+}