On a gas planet the vents were drawn on top of the player. SurfaceFeatures
is added after Fleet in PlanetSurface.tscn, so at the default z_index of 0
the vent field won the tie purely by being the later sibling, and the fleet
flew under its own gas source.
Same one-line fix, for the same reason, as #50's capture rings and the
rocks on a rocky surface. It goes on the field rather than on children
because this one draws in its own _draw().
The test checks the rule instead of the node that was wrong: every drawing
feature, on every surface profile that has features, must end up behind the
fleet - 22 of them today, and any added later without editing the test.
Enemies are excluded and the test says why; they are combatants and share
the fleet's plane on purpose.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
