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/Tasks/TaskPlanner.cs

@@ -20,10 +20,12 @@ public sealed class TaskPlanner : IDisposable
     private readonly IAgentStore _agents;
     private readonly IProbeStore _probes;
     private readonly ISettingsStore _settings;
+    private readonly LinkService _links;
     private readonly SemaphoreSlim _gate = new(1, 1);
 
-    public TaskPlanner(ITaskStore tasks, IAgentStore agents, IProbeStore probes, ISettingsStore settings)
+    public TaskPlanner(ITaskStore tasks, IAgentStore agents, IProbeStore probes, ISettingsStore settings, LinkService links)
     {
+        _links = links;
         _tasks = tasks;
         _agents = agents;
         _probes = probes;
@@ -41,6 +43,7 @@ public sealed class TaskPlanner : IDisposable
 
         IReadOnlyList<TaskRecord> all = await _tasks.ListAsync(ct);
         IReadOnlyList<ProbeRecord> probes = await _probes.ListAsync(ct);
+        LinkSnapshot links = await _links.SnapshotAsync(ct);
 
         var document = new TaskSet();
         foreach (EffectiveTask task in EffectiveTasks.Compute(all, agent, filterByAgentKinds: true))
@@ -57,7 +60,7 @@ public sealed class TaskPlanner : IDisposable
             });
         }
 
-        foreach (ProbeRecord probe in probes.Where(p => p.RevokedAtMs is null))
+        foreach (ProbeRecord probe in probes.Where(p => p.RevokedAtMs is null && links.IsLinked(p.Id, agentId.Value)))
         {
             document.Peers.Add(new PeerSpec { ProbeId = new ProbeId(probe.Id), PublicKey = Convert.ToBase64String(probe.PublicKey) });
         }