feat: Implement copying to clipboard for snapshot id of backups

lib/ui/pages/backups/snapshot_id_list_tile.dart

@@ -0,0 +1,52 @@
+import 'dart:async';
+
+import 'package:easy_localization/easy_localization.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+
+class SnapshotIdListTile extends StatefulWidget {
+  const SnapshotIdListTile({
+    required this.snapshotId,
+    super.key,
+  });
+
+  final String snapshotId;
+
+  @override
+  State<SnapshotIdListTile> createState() => _SnapshotIdListTileState();
+}
+
+class _SnapshotIdListTileState extends State<SnapshotIdListTile> {
+  bool copiedToClipboard = false;
+
+  void handleTimeout() {
+    setState(() {
+      copiedToClipboard = false;
+    });
+  }
+
+  @override
+  Widget build(final BuildContext context) => ListTile(
+        onLongPress: () {
+          if (copiedToClipboard == false) {
+            Clipboard.setData(ClipboardData(text: widget.snapshotId));
+            Timer(const Duration(seconds: 2), handleTimeout);
+            setState(() {
+              copiedToClipboard = true;
+            });
+          }
+        },
+        leading: Icon(
+          Icons.numbers_outlined,
+          color: Theme.of(context).colorScheme.onSurface,
+        ),
+        title: Text(
+          copiedToClipboard
+              ? 'basis.copied_to_clipboard'.tr()
+              : 'backup.snapshot_id_title'.tr(),
+        ),
+        subtitle: Text(
+          copiedToClipboard ? '' : widget.snapshotId,
+        ),
+      );
+}

lib/ui/pages/backups/snapshot_modal.dart

@@ -11,6 +11,7 @@ import 'package:selfprivacy/logic/models/service.dart';
 import 'package:selfprivacy/ui/components/buttons/brand_button.dart';
 import 'package:selfprivacy/ui/components/cards/outlined_card.dart';
 import 'package:selfprivacy/ui/components/info_box/info_box.dart';
+import 'package:selfprivacy/ui/pages/backups/snapshot_id_list_tile.dart';
 
 class SnapshotModal extends StatefulWidget {
   const SnapshotModal({
@@ -95,18 +96,7 @@ class _SnapshotModalState extends State<SnapshotModal> {
             '${MaterialLocalizations.of(context).formatShortDate(widget.snapshot.time)} ${TimeOfDay.fromDateTime(widget.snapshot.time).format(context)}',
           ),
         ),
-        ListTile(
+        SnapshotIdListTile(snapshotId: widget.snapshot.id),
-          leading: Icon(
-            Icons.numbers_outlined,
-            color: Theme.of(context).colorScheme.onSurface,
-          ),
-          title: Text(
-            'backup.snapshot_id_title'.tr(),
-          ),
-          subtitle: Text(
-            widget.snapshot.id,
-          ),
-        ),
         if (service != null)
           Column(
             children: [