test(console): make ConsoleInputPump prompt tests deterministic

Replace Thread.Sleep-based synchronization with waits on real state
(HasPendingPrompt / reader call count) so the rendezvous tests no longer
race on slow CI runners (CentOS 9, Ubuntu 22, macOS 15/26).

Projects/Server/Console/ConsoleInputPump.cs

@@ -35,6 +35,19 @@ internal sealed class ConsoleInputPump
 
     public bool Running => _running;
 
+    // Test-observable: true while a ReadLine() caller is registered and waiting for the
+    // next line. Lets tests synchronize on the rendezvous state instead of sleeping.
+    internal bool HasPendingPrompt
+    {
+        get
+        {
+            lock (_gate)
+            {
+                return _promptPending;
+            }
+        }
+    }
+
     public void Run()
     {
         try