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>

test/netfox/time/network-tickrate-handshake.test.gd

@@ -0,0 +1,69 @@
+extends VestTest
+
+func get_suite_name() -> String:
+	return "NetworkTickrateHandshake"
+
+func suite() -> void:
+	var base_tickrate := 60
+	var mismatching_tickrate := 48
+	
+	on_case_begin.connect(func(__):
+		# Reset tickrate
+		NetworkMocks.set_tickrate(base_tickrate)
+	)
+	
+	test("client should disconnect on mismatch", func():
+		# Difficult to pretend we're a client AND detect a disconnect
+		todo()
+	)
+
+	test("client should adjust on mismatch", func():
+		var handshake := await get_handshake(false)
+		handshake.mismatch_action = NetworkTickrateHandshake.ADJUST
+		
+		handshake.submit_tickrate(mismatching_tickrate)
+		expect_equal(NetworkTime.tickrate, mismatching_tickrate, "Tickrate was not adjusted!")
+	)
+
+	test("server should not adjust on mismatch", func():
+		var handshake := await get_handshake(true)
+		handshake.mismatch_action = NetworkTickrateHandshake.ADJUST
+		
+		handshake.submit_tickrate(mismatching_tickrate)
+		expect_equal(NetworkTime.tickrate, base_tickrate, "Tickrate was adjusted!")
+	)
+
+	test("client should emit signal on mismatch", func():
+		var handshake := await get_handshake(false)
+		handshake.mismatch_action = NetworkTickrateHandshake.SIGNAL
+		capture_signal(handshake.on_tickrate_mismatch, 2)
+		
+		handshake.submit_tickrate(mismatching_tickrate)
+		
+		expect_equal(
+			get_signal_emissions(handshake.on_tickrate_mismatch),
+			[[0, mismatching_tickrate]]
+		)
+	)
+
+func get_handshake(is_authority: bool) -> TestingTickrateHandshake:
+	var handshake := TestingTickrateHandshake.new(is_authority)
+	
+	# Add to tree
+	# TODO(vest): Use Vest.get_tree() after upgrade
+	Vest._scene_tree.root.add_child.call_deferred(handshake)
+	await handshake.ready
+	
+	return handshake
+
+class TestingTickrateHandshake extends NetworkTickrateHandshake:
+	var _is_tickrate_auth: bool
+	
+	func _init(p_is_tickrate_auth: bool):
+		_is_tickrate_auth = p_is_tickrate_auth
+	
+	func submit_tickrate(tickrate: int):
+		_submit_tickrate(tickrate)
+		
+	func _is_authority() -> bool:
+		return _is_tickrate_auth