Maps are editor-built scenes: [Tool] Playground/Crag, headless rebuild for agents

scenes/maps/playground.tscn and crag.tscn are generated by the map scripts' Rebuild (inspector
button, or godot-mono --headless --path . tools/rebuild_maps.tscn) and loaded as saved by the game,
so hand edits stick. The crag route is saved as Marker3D nodes and crag_spike checks the saved
scene. Layout verified identical to the code-built one (tools/map_dump.tscn).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

scenes/main.tscn

@@ -10,8 +10,8 @@
 [ext_resource type="Script" path="res://scripts/Calibration.cs" id="12_calibration"]
 [ext_resource type="Script" path="res://scripts/TrueBody.cs" id="13_truebody"]
 [ext_resource type="Script" path="res://scripts/PlayerRig.cs" id="14_playerrig"]
-[ext_resource type="Script" path="res://scripts/Playground.cs" id="15_playground"]
-[ext_resource type="Script" path="res://scripts/Crag.cs" id="16_crag"]
+[ext_resource type="PackedScene" path="res://scenes/maps/playground.tscn" id="15_playground"]
+[ext_resource type="PackedScene" path="res://scenes/maps/crag.tscn" id="16_crag"]
 
 [sub_resource type="ProceduralSkyMaterial" id="ProceduralSkyMaterial_sky"]
 sky_horizon_color = Color(0.66, 0.72, 0.81, 1)
@@ -109,11 +109,9 @@ script = ExtResource("3_locomotion")
 [node name="AnchorMoveMode" type="Node" parent="."]
 script = ExtResource("5_anchormove")
 
-[node name="Playground" type="Node3D" parent="."]
-script = ExtResource("15_playground")
+[node name="Playground" parent="." instance=ExtResource("15_playground")]
 
-[node name="Crag" type="Node3D" parent="."]
-script = ExtResource("16_crag")
+[node name="Crag" parent="." instance=ExtResource("16_crag")]
 
 [node name="PropShop" type="Node3D" parent="."]
 script = ExtResource("6_propshop")