Add tentacled boss planet encounter

surface/PlanetSurfaceProfile.gd

@@ -6,6 +6,12 @@ extends Resource
 
 @export var profile_id: String = "rocky"
 @export var features_scene: PackedScene
+# Optional self-contained gameplay encounter. Unlike an authored PlanetSetup,
+# this owns its own objectives and layout and is therefore not configurable in
+# the setup editor.
+@export var encounter_scene: PackedScene
+@export var editor_visible: bool = true
+@export var show_capture_status: bool = true
 # Which shader draws this surface's backdrop. Every profile names one - the
 # old "null means keep whatever the scene already had" convention is what let
 # the game and the setup editor drift apart, since each scene "already had" a