feat!: probes link to the panel; signed release updates for container nodes [CI]

Probes connect to the panel directly and get the agent list as desired state.
CI signs the image digest of agent and probe releases, the panel forwards the
manifest, and a host updater verifies it with a local public key, pulls by
digest and rolls back when the new version is unhealthy.

backend/tests/Monitor.TestSupport/AgentSimulator.cs

@@ -46,10 +46,15 @@ public sealed class AgentSimulator : IAsyncDisposable
 
     public ConcurrentQueue<TaskSet> TaskSets { get; } = new();
 
-    public ConcurrentQueue<ProbeAgentsResult> ProbeAgentLists { get; } = new();
-
     public ConcurrentQueue<TestRunParams> TestRuns { get; } = new();
 
+    /// <summary>面板发来的发布清单（<c>monitor.update.offer</c>）和更新请求（<c>monitor.update.apply</c>）。</summary>
+    public ConcurrentQueue<UpdateOfferParams> UpdateOffers { get; } = new();
+
+    private int _updateApplies;
+
+    public int UpdateApplies => Volatile.Read(ref _updateApplies);
+
     public ConcurrentQueue<TestId> TestCancels { get; } = new();
 
     public IReadOnlyList<RejectedItem> RejectNextState { get; set; } = [];
@@ -190,11 +195,12 @@ public sealed class AgentSimulator : IAsyncDisposable
             new TestStatusParams { TestId = test, Status = status, Phase = phase, ErrorCode = errorCode },
             MonitorJsonContext.Default.TestStatusParams));
 
-    public async Task<ProbeAgentsResult> RequestProbeAgentsAsync()
-    {
-        RpcMessage reply = await RequestAsync(MonitorMethods.ProbeAgents, JsonSerializer.SerializeToElement(new ProbeAgentsParams(), MonitorJsonContext.Default.ProbeAgentsParams));
-        return reply.Result!.Value.Deserialize(MonitorJsonContext.Default.ProbeAgentsResult)!;
-    }
+    /// <summary>像节点的更新器报告的那样，随心跳上报更新状态。</summary>
+    public Task SendUpdateStatusAsync(UpdateStatus status) =>
+        SendAsync(RpcMessage.Notification(
+            FleetMethods.Heartbeat,
+            new HeartbeatParams { Extra = JsonSerializer.SerializeToElement(new AgentHeartbeatExtra { Update = status }, MonitorJsonContext.Default.AgentHeartbeatExtra) },
+            FleetRpcContext.Default.HeartbeatParams));
 
     public async Task<RpcMessage> RequestRawAsync(string method, JsonElement? parameters = null) => await RequestAsync(method, parameters);
 
@@ -397,6 +403,12 @@ public sealed class AgentSimulator : IAsyncDisposable
             case FleetMethods.Revoked:
                 Revoked = true;
                 break;
+            case MonitorMethods.UpdateOffer:
+                UpdateOffers.Enqueue(message.Params!.Value.Deserialize(MonitorJsonContext.Default.UpdateOfferParams)!);
+                break;
+            case MonitorMethods.UpdateApply:
+                Interlocked.Increment(ref _updateApplies);
+                break;
             case MonitorMethods.TestRun:
                 TestRunParams run = message.Params!.Value.Deserialize(MonitorJsonContext.Default.TestRunParams)!;
                 TestRuns.Enqueue(run);
@@ -416,9 +428,6 @@ public sealed class AgentSimulator : IAsyncDisposable
                 TestCancels.Enqueue(cancel.TestId);
                 await SendAsync(RpcMessage.Success(message.Id!.Value, new TestRunResult { Accepted = true }, MonitorJsonContext.Default.TestRunResult));
                 break;
-            case MonitorMethods.ProbeAgentsChanged:
-                ProbeAgentLists.Enqueue(message.Params!.Value.Deserialize(MonitorJsonContext.Default.ProbeAgentsResult)!);
-                break;
         }
     }
 }

backend/tests/Monitor.TestSupport/ProbeSimulator.cs

@@ -61,8 +61,6 @@ public sealed class ProbeSimulator : IAsyncDisposable
 
     public ConcurrentQueue<TestId> Aborts { get; } = new();
 
-    public ConcurrentQueue<ProbeAgentsResult> AgentLists { get; } = new();
-
     public bool IsConnected => _rpc is not null && !_stop.IsCancellationRequested;
 
     public long NowUs() => (TimeProvider.System.GetTimestamp() - _origin) * 1_000_000 / TimeProvider.System.TimestampFrequency;
@@ -347,14 +345,6 @@ public sealed class ProbeSimulator : IAsyncDisposable
                     probe.Aborts.Enqueue(abort.TestId);
                     return ValueTask.CompletedTask;
                 })
-            .OnNotify(
-                MonitorMethods.ProbeAgentsChanged,
-                MonitorJsonContext.Default.ProbeAgentsResult,
-                (probe, list, _) =>
-                {
-                    probe.AgentLists.Enqueue(list);
-                    return ValueTask.CompletedTask;
-                })
             .OnNotify(
                 FleetMethods.OutboxAck,
                 FleetRpcContext.Default.OutboxAckParams,