fix(console): restore pump error logging; drop unused Stop; stop invalidating help cache on lookup

- ConsoleInputPump gains an optional ILogger so the reader-fault and
  command-dispatch catch blocks log warnings/errors again, matching the
  behavior the old ConsoleInputHandler had before the pump refactor.
- Remove ConsoleInputPump.Stop() — dead code, nothing calls it; the reader
  thread already terminates on EOF/Core.Closing/finally cleanup.
- GetInputCommand no longer clears the help-description cache on every
  lookup; RegisterCommand/UnregisterInputCommand still invalidate it
  correctly on the paths that actually change the command set.

Projects/Server/Console/ConsoleInputHandler.cs

@@ -69,7 +69,6 @@ public static class ConsoleInputHandler
         lock (_inputCommands)
         {
             var action = _inputCommands.GetValueOrDefault(command)?.Function;
-            _commandDescriptions = null;
             return action;
         }
     }
@@ -88,7 +87,7 @@ public static class ConsoleInputHandler
             return;
         }
 
-        _pump = new ConsoleInputPump(Console.In, GetInputCommand);
+        _pump = new ConsoleInputPump(Console.In, GetInputCommand, logger);
 
         new Thread(_pump.Run)
         {