Co-op pass: host-disconnect handling, spectate, late-join wave sync

- Clients now handle the host closing the arena: bank winnings if
  still alive (retire), reset the HUD, and return to the camp menu
  instead of being stranded in a dead world
- Death in co-op offers Spectate when a teammate is still fighting:
  closes the results overlay and watches the run; the escape menu
  gains a "Back to Camp" option for dead spectators to leave later
- Late joiners receive the current wave number on connect so their
  HUD doesn't sit on "Prepare..." until the next wave starts

level/scripts/level.gd

@@ -45,6 +45,9 @@ func _ready():
 	# Reshape the menu into the gladiator outfitting screen
 	_setup_outfitting_menu()
 
+	# Clients: if the host closes the arena, bank winnings and return to camp
+	Network.server_disconnected.connect(_on_server_closed)
+
 	# Create or find weapons container
 	if has_node("WeaponsContainer"):
 		weapons_container = get_node("WeaponsContainer")
@@ -81,6 +84,19 @@ func _on_connected_to_server():
 	print("[Level] Connected to server! Cleaning up manual weapons")
 	_cleanup_manual_weapons_on_client()
 
+## The host closed the arena while we were connected (client side).
+## Leaving alive counts as retiring - bank everything, then back to camp.
+func _on_server_closed():
+	print("[Level] Server disconnected - returning to camp")
+	if GameState.run_active:
+		GameState.retire_run()
+
+	if has_node("/root/HUD"):
+		get_node("/root/HUD").reset()
+
+	Input.mouse_mode = Input.MOUSE_MODE_VISIBLE
+	get_tree().reload_current_scene()
+
 ## Called by Network when multiplayer peer is set up
 func initialize_multiplayer():
 	print("[Level] initialize_multiplayer called. is_server: ", multiplayer.is_server())
@@ -235,6 +251,9 @@ func _on_player_connected(peer_id, player_info):
 		for orb_id in _active_orbs.keys():
 			rpc_id(peer_id, "_spawn_health_orb_local", orb_id, _active_orbs[orb_id])
 
+		# Sync the current wave number so the late joiner's HUD isn't stuck on "Prepare..."
+		GameState.rpc_id(peer_id, "sync_wave", GameState.current_wave)
+
 		# Sync equipped weapons for all existing players to the newly joined player
 		print("[Server] Syncing equipped weapons to newly connected peer: ", peer_id)
 		for player_node in players_container.get_children():