P7.9: fix headless export — resolve Resource class_name ordering + duplicate RoundManager + simulation stub API

- Fix dead code in server_main.gd (unreachable lag compensation print)
- Remove WeaponData type hints from weapon_server.gd (Resource class_name in Node scripts = headless fail)
- Use preload() instead of WeaponData class_name in weapon_definitions.gd for const refs
- Lazy-init WEAPONS dict (const can't reference preload members)
- Remove duplicate class_name RoundManager from server/scripts/round/round_manager.gd
- Remove DamageProcessor type hints from round/round_manager.gd and bomb_objective.gd
- Add start()/stop()/can_tick()/tick()/spawn_entity()/despawn_entity() to simulation_server_stub.gd
- Fix get_world_3d() → get_tree().root.world_3d in weapon_server.gd Node context
- Fix var data := → var data = for untyped WeaponDefinitions.get_weapon() returns
- Clean export cache and verify server starts with zero parse errors

server/scripts/simulation_server_stub.gd

@@ -31,6 +31,8 @@ var _weapon_config: Dictionary = {}
 var _history_depth: int = 64
 var _next_entity_id: int = 1
 var _entities: Dictionary = {}  # entity_id → StubEntity
+var _running: bool = false
+var _last_hit_result: Dictionary = {}
 
 # ---------------------------------------------------------------------------
 # SimulationServer API
@@ -50,6 +52,28 @@ func set_weapon_config(cfg: Dictionary) -> void:
 func set_history_depth(depth: int) -> void:
 	_history_depth = depth
 
+func start() -> void:
+	_running = true
+
+func stop() -> void:
+	_running = false
+
+func can_tick(delta: float) -> bool:
+	return _running
+
+func tick() -> PackedByteArray:
+	# Stub: returns empty snapshot
+	return PackedByteArray()
+
+func get_stats() -> Dictionary:
+	return {
+		"tick_count": 0,
+		"entity_count": _entities.size(),
+	}
+
+func get_last_hit_result() -> Dictionary:
+	return _last_hit_result
+
 func apply_input(entity_id: int, input_dict: Dictionary) -> void:
 	var e: StubEntity = _entities.get(entity_id)
 	if e == null:
@@ -75,10 +99,9 @@ func fire_weapon(entity_id: int) -> void:
 func get_entity(entity_id: int) -> StubEntity:
 	return _entities.get(entity_id)
 
-func spawn_player_entity(peer_id: int, pos: Vector3) -> int:
+func spawn_entity(pos: Vector3) -> int:
 	var e = StubEntity.new()
 	e.id = _next_entity_id
-	e.peer_id = peer_id
 	e.position = pos
 	e.alive = true
 	e.health = 100.0
@@ -86,12 +109,15 @@ func spawn_player_entity(peer_id: int, pos: Vector3) -> int:
 	_next_entity_id += 1
 	return e.id
 
-func despawn_player_entity(entity_id: int) -> void:
-	_entities.erase(entity_id)
+func spawn_player_entity(peer_id: int, pos: Vector3) -> int:
+	var entity_id = spawn_entity(pos)
+	var e: StubEntity = _entities.get(entity_id)
+	if e:
+		e.peer_id = peer_id
+	return entity_id
 
-func tick(delta: float) -> void:
-	# Stub: in the real C++ SimulationServer this runs the 128Hz simulation
-	pass
+func despawn_entity(entity_id: int) -> void:
+	_entities.erase(entity_id)
 
 func get_entity_count() -> int:
 	return _entities.size()