feat: choose probe/agent links from the admin, fix the overview popover [CI]

The panel decides which probes link to which agents (probes dial out): an
auto-link setting plus per-pair manual overrides with a link matrix in the
admin, and the hovered overview card is lifted above its neighbours.

backend/src/Monitor.Backend.Application/Query/Lines.cs

@@ -39,19 +39,22 @@ public sealed class LineService
 {
     private readonly AgentService _agents;
     private readonly IProbeStore _probes;
+    private readonly LinkService _links;
 
-    public LineService(AgentService agents, IProbeStore probes)
+    public LineService(AgentService agents, IProbeStore probes, LinkService links)
     {
+        _links = links;
         _agents = agents;
         _probes = probes;
     }
 
-    /// <summary>所有线路：每个 Agent 和每个<b>未吊销</b>的 Probe 配成一对。</summary>
+    /// <summary>所有线路：每个 Agent 和每个<b>未吊销</b>的 Probe 配成一对，只留下线路开着的（见 <see cref="LinkService"/>）；关掉的线路历史数据还在，按 id 仍然查得到。</summary>
     public async ValueTask<IReadOnlyList<LineView>> ListAsync(Func<AgentView, bool> include, CancellationToken ct)
     {
         IReadOnlyList<AgentView> agents = await _agents.ListAsync(ct);
         IReadOnlyList<ProbeRecord> probes = [.. (await _probes.ListAsync(ct)).Where(p => p.RevokedAtMs is null)];
-        return [.. agents.Where(include).SelectMany(a => probes.Select(p => new LineView(a, p)))];
+        LinkSnapshot links = await _links.SnapshotAsync(ct);
+        return [.. agents.Where(include).SelectMany(a => probes.Where(p => links.IsLinked(p.Id, a.Agent.Id.Value)).Select(p => new LineView(a, p)))];
     }
 
     /// <summary>