experimental: remove Tekton Doors entirely

- Delete portal_mode_manager.gd, portal_door.gd, portal_door.tscn
- Strip all Tekton Doors logic from main.gd, player.gd, lobby.gd,
  lobby_room.gd, lobby_manager.gd, camera_context_manager.gd,
  music_manager.gd, tekton.gd, enhanced_gridmap.gd,
  playerboard_manager.gd, special_tiles_manager.gd
- Remove TK enum (TEKTON_DOORS=2), mode_config schema, arena area
- Update tests: 3 modes instead of 4
- Strip HowToPlay tab from main.tscn

test_ssh.sh

@@ -0,0 +1,5 @@
+#!/usr/bin/expect -f
+spawn ssh admin@193.180.213.215 "ls -la /home/admin/nakama/data/modules/"
+expect "password:"
+send "Mieayamtelur17\r"
+expect eof