Add the planet setup map editor (#48)

PlanetSetupEditor authors PlanetSetup resources: pick a surface
profile (drives the real lunar_surface background, not a blank
sheet), place/move/delete capture points and enemies from a palette
generated straight off EnemyDefinitions.all() (a new enemy definition
shows up with no editor change), pan/pinch-zoom the canvas with the
same touch idiom as GameController, then save to
res://PlanetSetups/<id>.tres via ResourceSaver - reachable now from
the main menu's Map Editor button. The mutation methods
(new_setup/load_setup/add_*/move_*/remove_*/save_setup) are the whole
model and work standalone, which is what lets
tests/test_setup_editor.gd drive placement/move/delete/save/reload
directly without simulating touch input.

Every cross-file reference is a preloaded script const rather than a
bare global class name, matching #42/#44's load-order notes - this
file is instantiated from other scripts' function bodies, never as a
script-mode test entry point itself, so it wasn't at risk the same way
the test files were, but the pattern is kept consistent throughout.

Part of the #40 conquest-mechanic breakdown. This closes out the
breakdown: #41-#48 are now all implemented, tested, and merged.

PlanetSetupEditor.tscn

@@ -0,0 +1,179 @@
+[gd_scene load_steps=5 format=3]
+
+[ext_resource type="Script" path="res://PlanetSetupEditor.gd" id="1"]
+[ext_resource type="Script" path="res://LunarBackground.gd" id="2"]
+[ext_resource type="Shader" path="res://lunar_surface.gdshader" id="3"]
+[ext_resource type="Script" path="res://IconButton.gd" id="4"]
+
+[sub_resource type="ShaderMaterial" id="1"]
+shader = ExtResource("3")
+shader_parameter/camera_zoom = 1.0
+shader_parameter/viewport_size = Vector2(720, 1280)
+shader_parameter/cell_size = 220.0
+shader_parameter/base_color = Color(0.75, 0.75, 0.76, 1)
+shader_parameter/crater_color = Color(0.44, 0.44, 0.45, 1)
+shader_parameter/highlight_color = Color(0.89, 0.89, 0.9, 1)
+
+[node name="PlanetSetupEditor" type="Node2D"]
+script = ExtResource("1")
+
+[node name="BackgroundLayer" type="CanvasLayer" parent="."]
+layer = -10
+
+[node name="Background" type="ColorRect" parent="BackgroundLayer"]
+material = SubResource("1")
+mouse_filter = 2
+anchors_preset = 15
+anchor_right = 1.0
+anchor_bottom = 1.0
+grow_horizontal = 2
+grow_vertical = 2
+script = ExtResource("2")
+
+[node name="Camera2D" type="Camera2D" parent="."]
+position = Vector2(0, 0)
+zoom = Vector2(1, 1)
+
+[node name="ItemHost" type="Node2D" parent="."]
+
+[node name="UI" type="CanvasLayer" parent="."]
+layer = 1
+
+[node name="BackButton" type="Control" parent="UI"]
+offset_left = 20
+offset_top = 20
+offset_right = 92
+offset_bottom = 92
+script = ExtResource("4")
+icon = 1
+glow_color = Color(0.9, 0.35, 0.35, 1)
+
+[node name="BackCaption" type="Label" parent="UI"]
+mouse_filter = 2
+offset_left = 20
+offset_top = 96
+offset_right = 92
+offset_bottom = 122
+theme_override_font_sizes/font_size = 18
+horizontal_alignment = 1
+text = "Back"
+
+[node name="ProfileButton" type="Control" parent="UI"]
+offset_left = 110
+offset_top = 20
+offset_right = 182
+offset_bottom = 92
+script = ExtResource("4")
+icon = 0
+glow_color = Color(0.5, 0.75, 1, 1)
+
+[node name="ProfileValueLabel" type="Label" parent="UI"]
+mouse_filter = 2
+offset_left = 190
+offset_top = 36
+offset_right = 340
+offset_bottom = 76
+theme_override_font_sizes/font_size = 26
+text = "ROCKY"
+
+[node name="NameInput" type="LineEdit" parent="UI"]
+offset_left = 350
+offset_top = 36
+offset_right = 696
+offset_bottom = 76
+placeholder_text = "Setup name"
+text = "Untitled"
+
+[node name="NewButton" type="Control" parent="UI"]
+offset_left = 20
+offset_top = 140
+offset_right = 92
+offset_bottom = 212
+script = ExtResource("4")
+icon = 5
+glow_color = Color(0.45, 0.9, 0.55, 1)
+
+[node name="NewCaption" type="Label" parent="UI"]
+mouse_filter = 2
+offset_left = 20
+offset_top = 216
+offset_right = 92
+offset_bottom = 242
+theme_override_font_sizes/font_size = 18
+horizontal_alignment = 1
+text = "New"
+
+[node name="SaveButton" type="Control" parent="UI"]
+offset_left = 110
+offset_top = 140
+offset_right = 182
+offset_bottom = 212
+script = ExtResource("4")
+icon = 4
+glow_color = Color(0.45, 0.9, 0.55, 1)
+
+[node name="SaveCaption" type="Label" parent="UI"]
+mouse_filter = 2
+offset_left = 110
+offset_top = 216
+offset_right = 182
+offset_bottom = 242
+theme_override_font_sizes/font_size = 18
+horizontal_alignment = 1
+text = "Save"
+
+[node name="LoadButton" type="Control" parent="UI"]
+offset_left = 200
+offset_top = 140
+offset_right = 272
+offset_bottom = 212
+script = ExtResource("4")
+icon = 3
+glow_color = Color(0.5, 0.75, 1, 1)
+
+[node name="LoadCaption" type="Label" parent="UI"]
+mouse_filter = 2
+offset_left = 200
+offset_top = 216
+offset_right = 272
+offset_bottom = 242
+theme_override_font_sizes/font_size = 18
+horizontal_alignment = 1
+text = "Load"
+
+[node name="DeleteButton" type="Control" parent="UI"]
+offset_left = 290
+offset_top = 140
+offset_right = 362
+offset_bottom = 212
+script = ExtResource("4")
+icon = 28
+glow_color = Color(0.9, 0.35, 0.35, 1)
+
+[node name="DeleteCaption" type="Label" parent="UI"]
+mouse_filter = 2
+offset_left = 290
+offset_top = 216
+offset_right = 362
+offset_bottom = 242
+theme_override_font_sizes/font_size = 18
+horizontal_alignment = 1
+text = "Delete"
+
+[node name="StatusLabel" type="Label" parent="UI"]
+mouse_filter = 2
+offset_left = 380
+offset_top = 140
+offset_right = 696
+offset_bottom = 242
+theme_override_font_sizes/font_size = 20
+autowrap_mode = 2
+text = ""
+
+[node name="PaletteRow" type="Control" parent="UI"]
+anchor_top = 1.0
+anchor_bottom = 1.0
+offset_left = 20
+offset_top = -110
+offset_right = 696
+offset_bottom = -20