feat(mobile,account-service): 统一发送服务 + 员工目录接口 + 好友申请五态/验证消息（B-52 施工 2/3）

- message_send_service：所有消息走统一门禁（登录/连接/空接收方/好友校验），
  失败打印 SDK 原始 code 并映射中文提示，不再只吞异常
- chat_screen 接入统一发送服务，失败提示真实原因
- account-service 新增 GET /api/directory（登录用户可读启用员工，用于添加同事）
- add_friend_screen 增加可编辑验证消息（视觉规范 4.2）
- new_friends_screen 五态 + 窄屏(<360)按钮组换行不挤压姓名（视觉规范 5.3）

Co-authored-by: multica-agent <github@multica.ai>

mobile/lib/screens/new_friends_screen.dart

@@ -98,43 +98,83 @@ class _NewFriendsScreenState extends State<NewFriendsScreen> {
 
   Widget _tile(FriendApplicationInfo a) {
     final name = a.fromNickname?.isNotEmpty == true ? a.fromNickname! : (a.fromUserID ?? '');
-    Widget trailing;
+    final isPending = a.handleResult == 0;
+    final showButtons = isPending;
+    // 窄屏（<360）时按钮组换到第二行右对齐，避免挤压姓名区
+    final narrow = MediaQuery.sizeOf(context).width < 360;
+
+    // 「接受/拒绝」按钮组：总宽固定 132，任何情况下不压缩、不换行
+    final buttonGroup = Row(
+      mainAxisSize: MainAxisSize.min,
+      children: [
+        FilledButton(
+          onPressed: () => _handle(a, true),
+          style: FilledButton.styleFrom(
+            backgroundColor: AppColors.primary,
+            minimumSize: const Size(60, 32),
+            padding: const EdgeInsets.symmetric(horizontal: AppGap.x3),
+          ),
+          child: const Text('接受', style: TextStyle(fontSize: AppFont.sub)),
+        ),
+        const SizedBox(width: AppGap.x2),
+        OutlinedButton(
+          onPressed: () => _handle(a, false),
+          style: OutlinedButton.styleFrom(
+            minimumSize: const Size(60, 32),
+            padding: const EdgeInsets.symmetric(horizontal: AppGap.x3),
+          ),
+          child: const Text('拒绝', style: TextStyle(fontSize: AppFont.sub)),
+        ),
+      ],
+    );
+
+    Widget statusText;
     if (a.handleResult == 1) {
-      trailing = const Text('已添加', style: TextStyle(fontSize: AppFont.sub, color: AppColors.textSecondary));
+      statusText = const Text('已添加', style: TextStyle(fontSize: AppFont.sub, color: AppColors.textSecondary));
     } else if (a.handleResult == -1) {
-      trailing = const Text('已拒绝', style: TextStyle(fontSize: AppFont.sub, color: AppColors.textSecondary));
+      statusText = const Text('已拒绝', style: TextStyle(fontSize: AppFont.sub, color: AppColors.textSecondary));
     } else {
-      trailing = Row(
-        mainAxisSize: MainAxisSize.min,
-        children: [
-          FilledButton(
-            onPressed: () => _handle(a, true),
-            style: FilledButton.styleFrom(
-              backgroundColor: AppColors.primary,
-              minimumSize: const Size(0, 32),
-              padding: const EdgeInsets.symmetric(horizontal: AppGap.x3),
-            ),
-            child: const Text('接受', style: TextStyle(fontSize: AppFont.sub)),
-          ),
-          const SizedBox(width: AppGap.x2),
-          OutlinedButton(
-            onPressed: () => _handle(a, false),
-            style: OutlinedButton.styleFrom(
-              minimumSize: const Size(0, 32),
-              padding: const EdgeInsets.symmetric(horizontal: AppGap.x3),
-            ),
-            child: const Text('拒绝', style: TextStyle(fontSize: AppFont.sub)),
-          ),
-        ],
-      );
+      statusText = const Text('等待对方通过', style: TextStyle(fontSize: AppFont.sub, color: AppColors.textSecondary));
     }
-    return ListTile(
-      leading: NameAvatar(name: name),
-      title: Text(name, style: const TextStyle(fontSize: AppFont.body)),
-      subtitle: a.reqMsg?.isNotEmpty == true
-          ? Text(a.reqMsg!, maxLines: 1, overflow: TextOverflow.ellipsis, style: const TextStyle(fontSize: AppFont.sub, color: AppColors.textSecondary))
-          : null,
-      trailing: trailing,
+
+    return Padding(
+      padding: const EdgeInsets.symmetric(horizontal: AppGap.x4, vertical: AppGap.x3),
+      child: Row(
+        crossAxisAlignment: CrossAxisAlignment.center,
+        children: [
+          NameAvatar(name: name),
+          const SizedBox(width: AppGap.x3),
+          Expanded(
+            child: Column(
+              crossAxisAlignment: CrossAxisAlignment.start,
+              mainAxisSize: MainAxisSize.min,
+              children: [
+                Text(
+                  name,
+                  maxLines: 1,
+                  overflow: TextOverflow.ellipsis,
+                  style: const TextStyle(fontSize: AppFont.body, color: AppColors.textPrimary),
+                ),
+                if (a.reqMsg?.isNotEmpty == true) ...[
+                  const SizedBox(height: AppGap.x1),
+                  Text(
+                    a.reqMsg!,
+                    maxLines: 1,
+                    overflow: TextOverflow.ellipsis,
+                    style: const TextStyle(fontSize: AppFont.sub, color: AppColors.textSecondary),
+                  ),
+                ],
+                if (narrow && showButtons) ...[
+                  const SizedBox(height: AppGap.x2),
+                  Align(alignment: Alignment.centerRight, child: buttonGroup),
+                ],
+              ],
+            ),
+          ),
+          if (!narrow)
+            SizedBox(width: 132, child: Align(alignment: Alignment.centerRight, child: showButtons ? buttonGroup : statusText)),
+        ],
+      ),
     );
   }
 }