refactor(link): bound every teardown and handler wait behind one helper [CI]

backend/fleet/src/Fleet.Rpc/RpcSession.cs

@@ -50,6 +50,7 @@ public sealed class RpcSession<TContext> : IAsyncDisposable
     private readonly IRpcTransport _transport;
     private readonly RpcRouter<TContext> _router;
     private readonly TContext _context;
+    private static readonly TimeSpan s_dispatcherGrace = TimeSpan.FromSeconds(5);
     private readonly TimeProvider _time;
     private readonly RpcSessionOptions _options;
     private readonly ConcurrentDictionary<long, TaskCompletionSource<RpcMessage>> _pending = new();
@@ -135,14 +136,8 @@ public sealed class RpcSession<TContext> : IAsyncDisposable
             }
 
             await linked.CancelAsync();
-            try
-            {
-                await dispatcher;
-            }
-            catch (OperationCanceledException)
-            {
-                // 正常结束
-            }
+            // 某个入站处理器卡住了也不能拖住整个会话的结束（链路据此重连）：它随取消令牌自己收尾
+            await Bounded.WaitAsync(dispatcher, s_dispatcherGrace, _time);
         }
     }