agent: unify listening and dialing with directed mutual measurements

Replace Probe with Agent across node runtime, Fleet contracts, backend state, API and storage. Report incoming sessions and outgoing link health through each Agent uplink, and retain directed link controls and retry.

Update protocol fixtures and end-to-end coverage for the unified model; accept requested cancellation during the Fleet timeout test cleanup.

backend/src/MoShiro.Backend.Api/Admin/TrustEndpoints.cs

@@ -39,7 +39,7 @@ public static class TrustEndpoints
     /// <summary>面板提供的脚本和 CI 签名的发布清单里记的哈希是否一致（清单由 CI 签名，节点和浏览器之外的人改不了）。没有清单或没记哈希时返回 null。</summary>
     private static async Task<bool?> MatchesReleaseAsync(ReleaseService releases, string sh, string ps1, CancellationToken ct)
     {
-        foreach (string component in new[] { JoinTokenService.AgentRole, JoinTokenService.ProbeRole })
+        foreach (string component in new[] { ReleaseService.AgentComponent })
         {
             if (await releases.GetAsync(component, ct) is not { } offer)
             {