Share one backdrop between game and editor, and fix three input/economy bugs

The setup editor and the landed surface drew different backgrounds for the
same planet. Each scene carried its own hand-written ShaderMaterial, and only
the game side ever swapped in a profile's shader, so a gas giant authored in
the editor showed recoloured craters while the game showed cloud bands. Both
now instance one SurfaceBackground.tscn and configure it through one method,
and every profile names its own shader - the old "null means keep whatever
the scene already had" convention was the drift, since each scene "already
had" something different. The shared material is resource_local_to_scene, or
two live surfaces would repaint each other.

The gas giant's bands broke into disjoint segments once per cell: the second
turbulence octave doubled only the INTEGER half of a lattice coordinate,
which is a different point in every cell rather than the same point at twice
the frequency. Measured, the old form steps 0.153 at a cell boundary against
0.0002 now. A second discontinuity went with it - the camera cell index
arrives pre-wrapped, so hashing it raw rearranged the whole sky every 32
cells; hashes are now wrapped per octave and the field is exactly periodic.
Bands also gained low-frequency octaves and per-row differential drift.

WorldMap swallowed every touch in _input(), which runs before the GUI system,
so CloseButton never saw one: the map could be opened and not closed. Android
and desktop hid it behind Godot's emulated mouse event, which this never
swallowed; a phone browser gives no such second chance. Its test had been
closing the map by calling the method the button was failing to reach.

Construction now draws on the fleet hold as well as the bank. With an empty
starting bank and ore bankable only at a mothership, charging construction to
the bank alone made the first mothership cost ore that could not yet exist.

Also: a conquered planet no longer re-spawns its garrison (guarded on having
capture points, since a setup with none registers as vacuously conquered);
planets keep the map they drew, with the candidate list sorted rather than
left in filesystem order and assignments pruned rather than cleared on
rescan; and the map editor lists setups at a tappable size and can delete
one, as an explicit armed mode rather than a tap away from destroying work.

Full suite 106/106.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

WorldMap.gd

@@ -40,14 +40,38 @@ func recenter_view() -> void:
 	content.position = viewport_center - fleet_local * content.scale.x
 
 
+# The map takes over touch input while it is open, so a drag pans the map
+# instead of ordering the fleet somewhere. What it must NOT take over is a
+# touch aimed at its own buttons.
+#
+# _input() runs BEFORE the GUI system, so set_input_as_handled() here stopped
+# the touch ever reaching CloseButton._gui_input: the map could be opened and
+# then not closed. On Android and desktop that stayed hidden, because Godot
+# also emits an emulated MOUSE event for each touch and this only ever
+# swallowed touch events - the button still got the mouse one, a second
+# chance a phone browser does not give. So it surfaced on the web build,
+# while being a real routing bug on every platform.
+#
+# Letting those events through is safe: IconButton consumes them with
+# accept_event(), which marks them handled before GameController's
+# _unhandled_input runs - so tapping Close still cannot also move the fleet.
 func _input(event: InputEvent) -> void:
 	if not visible:
 		return
 
 	if event is InputEventScreenTouch:
+		# A press over one of the map's own buttons is never adopted, and
+		# because it is never adopted, neither is anything else that touch
+		# goes on to do - the index simply never enters `touches`.
+		if event.pressed and _over_own_button(event.position):
+			return
+		if not event.pressed and not touches.has(event.index):
+			return
 		_handle_touch(event)
 		get_viewport().set_input_as_handled()
 	elif event is InputEventScreenDrag:
+		if not touches.has(event.index):
+			return
 		_handle_drag(event)
 		get_viewport().set_input_as_handled()
 	elif event is InputEventMagnifyGesture:
@@ -55,6 +79,18 @@ func _input(event: InputEvent) -> void:
 		get_viewport().set_input_as_handled()
 
 
+# Asked of the children rather than listed by name, so a button added to the
+# map panel later is covered without anyone having to remember this exists.
+# Keyed on having a `pressed` signal: the backdrop is a full-screen ColorRect
+# and would otherwise match every point on the display.
+func _over_own_button(at: Vector2) -> bool:
+	for child in get_children():
+		if child is Control and child.visible and child.has_signal("pressed") \
+				and (child as Control).get_global_rect().has_point(at):
+			return true
+	return false
+
+
 func _handle_touch(event: InputEventScreenTouch) -> void:
 	if event.pressed:
 		touches[event.index] = event.position