feat: synchronize authoritative npc position

- NpcVisual emits position_changed signal during _physics_process
- SimulationManager.synchronize_npc_position() writes active position
  into SimNPC state on movement, arrival, and navigation failure
- WorldViewManager forwards position_changed and syncs before
  despawn/reload
- SimNPC stores travel_target_position and has_travel_target as
  versioned state; NPCStateRecord v2 persists them with v1 migration
- WorldViewManager.spawn_npc_visual() resumes travel for traveling NPCs
  via SimulationManager.request_current_travel()
- WorldViewManager.despawn_npc_visual() syncs position before removal
- WorldViewManager.reload_npc_visual() spawns a visual from persisted
  state without rerolling target selection
- tests/npc_visual_lifecycle_test.gd proves unload/reload preserves
  action, target, reservation, position, RNG state, and checksum
- simulation_state_serialization_test adds legacy v1 NPC migration test
  that does not invent an active travel target

simulation/SimNPC.gd

@@ -26,6 +26,8 @@ var task_duration := 0.0
 var task_progress := 0.0
 var task_complete := true
 var target_id: StringName = &""
+var travel_target_position: Vector3
+var has_travel_target := false
 var last_task: StringName
 var random_source: RandomNumberGenerator
 var debug_logs := true
@@ -62,6 +64,7 @@ func die_from_starvation() -> void:
 	task_progress = 0.0
 	task_duration = 0.0
 	task_complete = true
+	has_travel_target = false
 
 	if debug_logs:
 		print("[SimNPC] ", npc_name, " died from starvation.")
@@ -85,6 +88,7 @@ func set_task(action_id: StringName, duration: float = -1.0) -> void:
 	task_progress = 0.0
 	task_complete = false
 	task_state = TASK_STATE_TRAVELING
+	has_travel_target = false
 
 func start_working() -> void:
 	if task_state != TASK_STATE_TRAVELING:

simulation/SimulationManager.gd

@@ -182,6 +182,7 @@ func simulate_tick() -> void:
 			npc.task_state = SimNPC.TASK_STATE_IDLE
 			npc.last_task = completed_task
 			npc.current_task = SimulationIds.ACTION_IDLE
+			npc.has_travel_target = false
 
 			if needs_immediate_food_after_gather and village.food > 0:
 				npc.set_task(SimulationIds.ACTION_EAT, 1.0)
@@ -262,6 +263,7 @@ func notify_npc_arrived(npc_id: int) -> void:
 						notify_npc_navigation_failed(npc.id)
 						return
 
+				npc.has_travel_target = false
 				npc.start_working()
 
 				if debug_logs:
@@ -308,10 +310,32 @@ func resolve_npc_target(npc_id: int, origin: Vector3) -> bool:
 			notify_npc_target_unavailable(npc.id)
 			return false
 		npc.target_id = StringName(result.get("target_id", ""))
-		npc_travel_requested.emit(npc, result["position"])
+		npc.travel_target_position = result["position"]
+		npc.has_travel_target = true
+		npc_travel_requested.emit(npc, npc.travel_target_position)
 		return true
 	return false
 
+func request_current_travel(npc_id: int) -> bool:
+	for npc in npcs:
+		if npc.id != npc_id:
+			continue
+		if npc.task_state != SimNPC.TASK_STATE_TRAVELING:
+			return false
+		if npc.has_travel_target:
+			npc_travel_requested.emit(npc, npc.travel_target_position)
+		else:
+			npc_target_requested.emit(npc)
+		return true
+	return false
+
+func synchronize_npc_position(npc_id: int, active_position: Vector3) -> bool:
+	for npc in npcs:
+		if npc.id == npc_id:
+			npc.position = active_position
+			return true
+	return false
+
 func register_loaded_resource_nodes() -> void:
 	for node in ResourceNode.get_all():
 		register_resource_node(node)
@@ -444,6 +468,12 @@ func get_state_snapshot() -> Dictionary:
 			"task_progress": npc.task_progress,
 			"target_id": String(npc.target_id),
 			"position": [npc.position.x, npc.position.y, npc.position.z],
+			"travel_target_position": [
+				npc.travel_target_position.x,
+				npc.travel_target_position.y,
+				npc.travel_target_position.z
+			],
+			"has_travel_target": npc.has_travel_target,
 			"starvation_ticks": npc.starvation_ticks,
 			"is_dead": npc.is_dead
 		})

simulation/state/NPCStateRecord.gd

@@ -1,7 +1,8 @@
 class_name NPCStateRecord
 extends RefCounted
 
-const SCHEMA_VERSION := 1
+const SCHEMA_VERSION := 2
+const LEGACY_SCHEMA_VERSION := 1
 
 var data: Dictionary
 
@@ -29,25 +30,41 @@ static func capture(npc: SimNPC) -> NPCStateRecord:
 		"task_progress": npc.task_progress,
 		"task_complete": npc.task_complete,
 		"target_id": String(npc.target_id),
+		"travel_target_position": [
+			npc.travel_target_position.x,
+			npc.travel_target_position.y,
+			npc.travel_target_position.z
+		],
+		"has_travel_target": npc.has_travel_target,
 		"last_task": String(npc.last_task),
 		"random_seed": str(npc.random_source.seed),
 		"random_state": str(npc.random_source.state)
 	})
 
 static func from_dictionary(record_data: Dictionary) -> NPCStateRecord:
-	if int(record_data.get("schema_version", -1)) != SCHEMA_VERSION:
+	var version := int(record_data.get("schema_version", -1))
+	if version == LEGACY_SCHEMA_VERSION:
+		record_data = _migrate_v1(record_data)
+	elif version != SCHEMA_VERSION:
 		return null
 	if not record_data.has_all([
 		"id", "name", "profession", "hunger", "energy", "strength",
 		"intelligence", "current_task", "task_state", "position",
 		"is_starving", "starvation_ticks", "starvation_death_threshold",
 		"is_dead", "task_duration", "task_progress", "task_complete",
-		"target_id", "last_task", "random_seed", "random_state"
+		"target_id", "travel_target_position", "has_travel_target",
+		"last_task", "random_seed", "random_state"
 	]):
 		return null
 	var saved_position = record_data["position"]
 	if not saved_position is Array or saved_position.size() != 3:
 		return null
+	var saved_target_position = record_data["travel_target_position"]
+	if (
+		not saved_target_position is Array
+		or saved_target_position.size() != 3
+	):
+		return null
 	var profession_id := StringName(record_data["profession"])
 	if SimulationDefinitions.get_profession(profession_id) == null:
 		return null
@@ -68,6 +85,16 @@ static func from_dictionary(record_data: Dictionary) -> NPCStateRecord:
 		return null
 	return NPCStateRecord.new(record_data)
 
+static func _migrate_v1(legacy_data: Dictionary) -> Dictionary:
+	var migrated := legacy_data.duplicate(true)
+	migrated["schema_version"] = SCHEMA_VERSION
+	migrated["travel_target_position"] = legacy_data.get(
+		"position",
+		[0.0, 0.0, 0.0]
+	)
+	migrated["has_travel_target"] = false
+	return migrated
+
 func restore(debug_logs: bool) -> SimNPC:
 	var random_source := RandomNumberGenerator.new()
 	random_source.seed = String(data["random_seed"]).to_int()
@@ -80,6 +107,7 @@ func restore(debug_logs: bool) -> SimNPC:
 		random_source
 	)
 	var saved_position: Array = data["position"]
+	var saved_target_position: Array = data["travel_target_position"]
 	npc.hunger = float(data["hunger"])
 	npc.energy = float(data["energy"])
 	npc.current_task = StringName(data["current_task"])
@@ -97,6 +125,12 @@ func restore(debug_logs: bool) -> SimNPC:
 	npc.task_progress = float(data["task_progress"])
 	npc.task_complete = bool(data["task_complete"])
 	npc.target_id = StringName(data["target_id"])
+	npc.travel_target_position = Vector3(
+		float(saved_target_position[0]),
+		float(saved_target_position[1]),
+		float(saved_target_position[2])
+	)
+	npc.has_travel_target = bool(data["has_travel_target"])
 	npc.last_task = StringName(data["last_task"])
 	npc.random_source.state = String(data["random_state"]).to_int()
 	npc.debug_logs = debug_logs