Phase 7: test server deployment + Windows export

- Fix: export_presets.cfg — platform='Windows Desktop' (correct name)
- Fix: server_main.gd — formatting bug on lag-comp string
- Fix: game_server.gd — auto-detect GDExtension, fall back to GDScript stub
- Add: server/scripts/simulation_server_stub.gd — lightweight SimulationServer in GDScript
- Add: docs/playtest-guide.md — connection instructions, control bindings, server commands
- Add: systemd user service — tactical-shooter-server (enabled, running)
- Add: server config at ~/tactical-shooter-server/server_config.cfg
- Build: Windows 109MB PE32+ client (build/tactical-shooter-windows-x86_64/)
- Build: Linux server binary (78MB) — running on oplabs:34197
- Temporarily disabled GDExtension (needs C++ build fix in entity.cpp enum casting)

server/scripts/game_server.gd

@@ -48,8 +48,11 @@ var entity_to_peer: Dictionary = {}  # entity_id (int) → peer_id (int)
 # ---------------------------------------------------------------------------
 
 func _ready() -> void:
-	# Create the SimulationServer
-	simulation_server = SimulationServer.new()
+	# Create the SimulationServer (stub if GDExtension not compiled)
+	var SimServerClass = load("res://server/scripts/simulation_server_stub.gd")
+	if ClassDB.class_exists(&"SimulationServer"):
+		SimServerClass = ClassDB.instantiate(&"SimulationServer").get_script()
+	simulation_server = SimServerClass.new()
 	simulation_server.set_tick_rate(128)
 
 	# Apply movement config from ServerConfig singleton if available

server/scripts/simulation_server_stub.gd

@@ -0,0 +1,97 @@
+## SimulationServerStub — lightweight GDScript replacement for GDExtension C++ core.
+##
+## Provides the same API surface so game_server.gd and FPSCharacterController
+## work without the compiled GDExtension library. No 128Hz simulation — just
+## stores entity state and passes through input. Replace with the C++
+## SimulationServer once `scons` builds cleanly.
+extends RefCounted
+
+# ---------------------------------------------------------------------------
+# Nested: Entity state data
+# ---------------------------------------------------------------------------
+class Entity:
+	var id: int = -1
+	var peer_id: int = -1
+	var position: Vector3 = Vector3.ZERO
+	var rotation: Vector3 = Vector3.ZERO
+	var velocity: Vector3 = Vector3.ZERO
+	var alive: bool = true
+	var health: float = 100.0
+	var input_sequence: int = 0
+
+	func is_alive() -> bool:
+		return alive
+
+# ---------------------------------------------------------------------------
+# Config
+# ---------------------------------------------------------------------------
+var _tick_rate: int = 128
+var _movement_config: Dictionary = {}
+var _weapon_config: Dictionary = {}
+var _history_depth: int = 64
+var _next_entity_id: int = 1
+var _entities: Dictionary = {}  # entity_id → Entity
+
+# ---------------------------------------------------------------------------
+# SimulationServer API
+# ---------------------------------------------------------------------------
+func set_tick_rate(hz: int) -> void:
+	_tick_rate = hz
+
+func get_tick_rate() -> int:
+	return _tick_rate
+
+func set_movement_config(cfg: Dictionary) -> void:
+	_movement_config = cfg
+
+func set_weapon_config(cfg: Dictionary) -> void:
+	_weapon_config = cfg
+
+func set_history_depth(depth: int) -> void:
+	_history_depth = depth
+
+func apply_input(entity_id: int, input_dict: Dictionary) -> void:
+	var e: Entity = _entities.get(entity_id)
+	if e == null:
+		return
+	# Apply movement from input (simplified)
+	if input_dict.has("move_direction"):
+		var dir: Vector3 = input_dict["move_direction"]
+		var speed: float = 5.0
+		if input_dict.get("sprint", false):
+			speed = 8.0
+		elif input_dict.get("crouch", false):
+			speed = 2.5
+		e.velocity = dir * speed
+		e.position += e.velocity * (1.0 / _tick_rate)
+	# Track input sequence
+	if input_dict.has("input_sequence"):
+		e.input_sequence = input_dict["input_sequence"]
+
+func fire_weapon(entity_id: int) -> void:
+	# Stub: log the event
+	pass
+
+func get_entity(entity_id: int) -> Entity:
+	return _entities.get(entity_id)
+
+func spawn_player_entity(peer_id: int, pos: Vector3) -> int:
+	var e = Entity.new()
+	e.id = _next_entity_id
+	e.peer_id = peer_id
+	e.position = pos
+	e.alive = true
+	e.health = 100.0
+	_entities[_next_entity_id] = e
+	_next_entity_id += 1
+	return e.id
+
+func despawn_player_entity(entity_id: int) -> void:
+	_entities.erase(entity_id)
+
+func tick(delta: float) -> void:
+	# Stub: in the real C++ SimulationServer this runs the 128Hz simulation
+	pass
+
+func get_entity_count() -> int:
+	return _entities.size()

server/scripts/simulation_server_stub.gd.uid

@@ -0,0 +1 @@
+uid://b1lw5s1djwsqk