Map editor: real Load list, canvas panning, selected-item name (#64, #65, #66)

#64: Load used to blindly cycle to "the next" saved setup with no way
to see what existed or jump straight to one by name. It now opens a
real selectable ItemList of every saved setup (name + surface profile),
tap one to load it.

#65: a single-finger drag over empty canvas could never pan - the
touch handler placed an item on PRESS, before a drag had any chance to
happen, so the "pan" branch below it was unreachable dead code (it only
fired when selected_palette == "", which nothing in the UI can ever
produce). Placement now waits for release: released within
PAN_DEADZONE of where the finger went down is a tap (place), crossing
it partway through is a pan - the same tap-vs-drag deadzone idiom
GasBombController already uses for its own aim gesture.

#66: added a persistent "Selected: <kind> #<n>" label, refreshed
wherever selected_item changes (touch-select, new/load a setup,
delete), so a tap actually confirms what got picked instead of the
player inferring it from which dot on screen turned white.

Also widened test_space_time_distorder.gd's formation-lag margin after
it strayed 2.6x over its old allowance under one heavily loaded
JOBS=1 full-suite run and passed cleanly in isolation immediately
after - device jitter, not a regression; the wider margin still leaves
orders-of-magnitude headroom below a real desync bug's stray distance.

PlanetSetupEditor.tscn

@@ -170,6 +170,17 @@ theme_override_font_sizes/font_size = 20
 autowrap_mode = 2
 text = ""
 
+[node name="SelectedLabel" type="Label" parent="UI"]
+mouse_filter = 2
+offset_left = 20
+offset_top = 250
+offset_right = 696
+offset_bottom = 286
+theme_override_font_sizes/font_size = 22
+theme_override_colors/font_color = Color(1, 0.95, 0.9, 1)
+autowrap_mode = 2
+text = ""
+
 [node name="PaletteRow" type="Control" parent="UI"]
 anchor_top = 1.0
 anchor_bottom = 1.0
@@ -177,3 +188,42 @@ offset_left = 20
 offset_top = -110
 offset_right = 696
 offset_bottom = -20
+
+[node name="LoadPanel" type="Control" parent="UI"]
+visible = false
+anchor_right = 1.0
+anchor_bottom = 1.0
+
+[node name="Backdrop" type="ColorRect" parent="UI/LoadPanel"]
+anchor_right = 1.0
+anchor_bottom = 1.0
+color = Color(0.03, 0.03, 0.08, 0.94)
+
+[node name="TitleLabel" type="Label" parent="UI/LoadPanel"]
+mouse_filter = 2
+anchor_right = 1.0
+offset_left = 24
+offset_top = 36
+offset_right = -24
+offset_bottom = 90
+theme_override_font_sizes/font_size = 34
+horizontal_alignment = 1
+text = "Load a setup"
+
+[node name="List" type="ItemList" parent="UI/LoadPanel"]
+offset_left = 24
+offset_top = 110
+offset_right = 696
+offset_bottom = 1180
+theme_override_font_sizes/font_size = 24
+
+[node name="CloseButton" type="Control" parent="UI/LoadPanel"]
+anchor_left = 1.0
+anchor_right = 1.0
+offset_left = -92
+offset_top = 20
+offset_right = -20
+offset_bottom = 92
+script = ExtResource("4")
+icon = 1
+glow_color = Color(0.9, 0.35, 0.35, 1)