Fix keyboard input not working on Windows client

Added explicit window focus grab after connecting (lan-bootstrapper.gd)
so keyboard input is properly received by the input system.
Also added diagnostic debug prints to trace input pipeline.

examples/multiplayer-fps/scripts/player-input.gd

@@ -75,12 +75,16 @@ func _input(event: InputEvent) -> void:
 
 func _gather():
 	if !is_setup:
+		print("[INPUT DEBUG] _gather first call - setting up")
 		setup()
-
+	
 	# Movement (continuous)
 	var mx = Input.get_axis("move_west", "move_east")
 	var mz = Input.get_axis("move_north", "move_south")
+	var old_mv = movement
 	movement = Vector3(mx, 0, mz)
+	if movement != old_mv and (mx != 0 or mz != 0):
+		print("[INPUT DEBUG] _gather movement=%s (mx=%.2f mz=%.2f)" % [movement, mx, mz])
 
 	jump = Input.is_action_pressed("move_jump")