feat: Add initial core game scene, player script, and static Tekton manager.

scenes/main.gd

@@ -528,6 +528,9 @@ func _setup_host_game():
 		stop_n_go_manager._setup_arena()
 	elif LobbyManager.game_mode == "Tekton Doors" and portal_mode_manager:
 		portal_mode_manager.setup_arena_locally()
+	else:
+		# Randomize grid first to ensure Floor 0 is walkable for pre-calculation
+		randomize_game_grid()
 		
 	# 1. PVT: Pre-calculate Static Tekton positions AFTER arena size is known
 	_precalculate_static_positions()
@@ -725,7 +728,6 @@ func _start_game():
 		# Spawn Static Tektons and random tiles BEFORE countdown (Free Mode Only)
 		# Exclude for Stop n Go and Tekton Doors
 		if LobbyManager.game_mode != "Stop n Go" and LobbyManager.game_mode != "Tekton Doors":
-			randomize_game_grid()
 			spawn_static_tektons()
 			
 		# Tekton Doors: Randomize connections BEFORE countdown so colors show