feat(telemetry): wire TelemetryDial:CallTimeoutSeconds as the dial-establishment deadline (A5)

CallTimeoutSeconds was bound, defaulted and documented but consumed
nowhere. TelemetryDialSupervisor now arms a per-generation deadline on
every dial: a dial that has delivered no event by the deadline is
cancelled and treated as a transport failure (reconnect with a failure
streak). A live node replays its snapshots on subscribe, so this bites
only a dial that never connects (a black-holed host, where the socket
connect has no timeout). An established stream is deliberately not
bounded — the wire has no heartbeat, keepalive pings own its liveness.

Review ref: 02/U2.

Refs #731

Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT

src/Core/ZB.MOM.WW.OtOpcUa.Cluster/TelemetryOptions.cs

@@ -72,7 +72,13 @@ public sealed class TelemetryDialOptions
     /// <summary>How often central refreshes its set of dialable node contacts, in seconds.</summary>
     public int ContactRefreshSeconds { get; set; } = 60;
 
-    /// <summary>Per-call deadline for a gRPC telemetry dial, in seconds.</summary>
+    /// <summary>
+    ///     Deadline, in seconds, for a gRPC telemetry dial to deliver its first event. A live node answers a
+    ///     fresh subscribe at once (it replays its health/resilience snapshots), so a dial still silent at the
+    ///     deadline is one that never connected — it is cancelled and re-dialled. Bounds establishment only;
+    ///     an established stream is kept alive by HTTP/2 keepalive pings, not by this value. Values below 1
+    ///     are treated as 1.
+    /// </summary>
     public int CallTimeoutSeconds { get; set; } = 30;
 }