mod: add skeleton

Signed-off-by: bggRGjQaUbCoE <githubaccount56556@proton.me>

lib/common/skeleton/msg_feed_sys_msg_.dart

@@ -0,0 +1,53 @@
+import 'package:flutter/material.dart';
+import 'skeleton.dart';
+
+class MsgFeedSysMsgSkeleton extends StatelessWidget {
+  const MsgFeedSysMsgSkeleton({super.key});
+
+  @override
+  Widget build(BuildContext context) {
+    final color = Theme.of(context).colorScheme.onInverseSurface;
+    return Skeleton(
+      child: Padding(
+        padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 12),
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            Container(
+              width: 125,
+              height: 16,
+              color: color,
+            ),
+            const SizedBox(height: 6),
+            Container(
+              width: double.infinity,
+              height: 12,
+              color: color,
+            ),
+            const SizedBox(height: 4),
+            Container(
+              width: double.infinity,
+              height: 12,
+              color: color,
+            ),
+            const SizedBox(height: 4),
+            Container(
+              width: 100,
+              height: 12,
+              color: color,
+            ),
+            const SizedBox(height: 4),
+            Align(
+              alignment: Alignment.centerRight,
+              child: Container(
+                width: 100,
+                height: 10,
+                color: color,
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}