fix(M03): support cold planner startup

Work-Package: M03-RND-STREAMING-PLANNER-001
Agent: sindo-main-codex
Tests: stale-class-cache headless planner verifier passes
Fidelity: type-resolution-only fix; planning behavior unchanged

src/render/streaming/streaming_target_planner.gd

@@ -14,8 +14,8 @@ const TARGET_PLAN_SCRIPT := preload("res://src/render/streaming/streaming_target
 func plan_runtime(
 		available_tile_paths_by_key: Dictionary,
 		focus_position: GodotWorldPosition,
-		policy: StreamingTargetPolicy
-) -> StreamingTargetPlan:
+		policy
+):
 	var focus_tile = COORDINATE_MAPPER_SCRIPT.godot_to_adt_tile(focus_position)
 	var prefetch_centers := _prefetch_centers(focus_position, focus_tile, policy)
 	var wanted_tile_keys := _available_keys_within_radius(
@@ -37,7 +37,7 @@ func plan_editor(
 		available_tile_paths_by_key: Dictionary,
 		focus_position: GodotWorldPosition,
 		editor_preview_tile_radius: int
-) -> StreamingTargetPlan:
+):
 	var focus_tile = COORDINATE_MAPPER_SCRIPT.godot_to_adt_tile(focus_position)
 	var centers: Array[AdtTileCoordinate] = [focus_tile]
 	var wanted_tile_keys := _available_keys_within_radius(
@@ -51,10 +51,10 @@ func plan_editor(
 func _prefetch_centers(
 		focus_position: GodotWorldPosition,
 		focus_tile: AdtTileCoordinate,
-		policy: StreamingTargetPolicy
+		policy
 ) -> Array[AdtTileCoordinate]:
 	var centers: Array[AdtTileCoordinate] = [focus_tile]
-	var threshold := policy.clamped_boundary_prefetch_threshold()
+	var threshold: float = policy.clamped_boundary_prefetch_threshold()
 	if threshold <= 0.0:
 		return centers