Fresh start: replace with naxIO/netfox-cs-sample foundation

Complete replacement of the tactical-shooter project with the
netfox-cs-sample (MIT) — a CS 1.6 inspired multiplayer FPS built
with Godot 4 and netfox.

## What's new
- Full CS-style gameplay: teams (T/CT), rounds, economy, buy menu
- 6 weapons: Knife, Glock, USP, AK-47, M4A1, AWP
- Bomb plant/defuse with 2 bombsites
- Flashbang & smoke grenades
- Proper netfox rollback netcode at 64 tick
- Network popup UI for host/join
- HUD, crosshair, round timer, scoreboard
- All netfox singletons registered as autoloads (works in exported builds)

## Architecture
- Listen-server (host from client, no dedicated server binary)
- Multiplayer-fps game lives at examples/multiplayer-fps/
- Netfox addons registered as autoloads for exported build compat
- Godot 4.7 with Forward+ renderer

## Removed
- Old headless-server architecture (client_main, server_main, player.gd, etc.)
- Custom netfox bootstrap with ENet fallback
- Old ChaffGames FPS template (2,420 lines, 844 KB)
- SimulationServer GDExtension stub
- Godot-jolt physics (netfox sample uses default Godot physics)
- Duplicate weapon_data.gd, anti_cheat.gd, round_manager.gd, etc.
- Server browser API Python venv (87 MB)
- test_range map and modular assets

## Preserved
- Git history
- Server config at config/default_server_config.cfg
- Windows export preset
- Build directory (gitignored)

Co-authored-by: naxIO <naxIO@users.noreply.github.com>

addons/netfox.extras/netfox-extras.gd

@@ -109,7 +109,8 @@ func _enter_tree():
 		add_setting(setting)
 
 	for autoload in AUTOLOADS:
-		add_autoload_singleton(autoload.name, autoload.path)
+		if not has_autoload(autoload.name):
+			add_autoload_singleton(autoload.name, autoload.path)
 	
 	for type in TYPES:
 		add_custom_type(type.name, type.base, load(type.script), load(type.icon))
@@ -122,7 +123,8 @@ func _exit_tree():
 			remove_setting(setting)
 
 	for autoload in AUTOLOADS:
-		remove_autoload_singleton(autoload.name)
+		if has_autoload(autoload.name):
+			remove_autoload_singleton(autoload.name)
 	
 	for type in TYPES:
 		remove_custom_type(type.name)
@@ -148,6 +150,9 @@ func remove_setting(setting: Dictionary):
 	
 	ProjectSettings.clear(setting.name)
 
+func has_autoload(name: String) -> bool:
+	return ProjectSettings.has_setting("autoload/" + name)
+
 func _render_tool_menu():
 	_free_tool_menu()
 	for driver_toggle in PhysicsDriverToggles.all():