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.

PaletteEntryButton.gd

@@ -0,0 +1,56 @@
+class_name PaletteEntryButton
+extends Control
+
+# One selectable tile in the setup editor's palette: either the generic
+# capture-point marker, or one enemy definition's own hull/colour. Drawn
+# directly from the definition rather than a fixed icon set, so a new
+# EnemyDefinitions entry shows up automatically with no editor code change.
+
+signal pressed
+
+@export var is_capture_point: bool = false
+@export var enemy_definition: Resource
+@export var selected: bool = false: set = set_selected
+
+const RING_COLOR: Color = Color(0.55, 0.85, 1.0)
+
+
+func set_selected(value: bool) -> void:
+	selected = value
+	queue_redraw()
+
+
+func _ready() -> void:
+	queue_redraw()
+
+
+func _gui_input(event: InputEvent) -> void:
+	if event is InputEventScreenTouch and not event.pressed \
+			and Rect2(Vector2.ZERO, size).has_point(event.position):
+		pressed.emit()
+	elif event is InputEventMouseButton and event.button_index == MOUSE_BUTTON_LEFT and not event.pressed:
+		pressed.emit()
+
+
+func _draw() -> void:
+	var center: Vector2 = size / 2.0
+	var margin: float = 4.0
+	var frame: PackedVector2Array = PackedVector2Array([
+		Vector2(margin, margin), Vector2(size.x - margin, margin),
+		Vector2(size.x - margin, size.y - margin), Vector2(margin, size.y - margin),
+	])
+	var frame_color: Color = Color(1.0, 0.95, 0.9) if selected else Color(0.4, 0.45, 0.5)
+	NeonDraw.draw_glowing_polygon(self, frame, frame_color, 0.85 if selected else 0.5)
+
+	if is_capture_point:
+		var points: PackedVector2Array = PackedVector2Array()
+		for i in range(16):
+			var angle: float = float(i) / 16.0 * TAU
+			points.append(center + Vector2(cos(angle), sin(angle)) * (size.x * 0.28))
+		NeonDraw.draw_glowing_polygon(self, points, RING_COLOR, 0.8)
+	elif enemy_definition != null:
+		var scale_factor: float = (size.x * 0.5) / 28.0
+		var points: PackedVector2Array = PackedVector2Array()
+		for p in enemy_definition.hull_points:
+			points.append(center + p * scale_factor * 0.6)
+		NeonDraw.draw_glowing_polygon(self, points, enemy_definition.glow_color, 0.9)