[AUSM] Actually Usable Shader Mod

Release 1.0.6

• Restored Advanced Rocketry space-station planet and sky textures with Complementary shaders, and disabled terrestrial light shafts in space to remove the white haze.

• Fixed missing shadows on small stations and islands by scaling shadow coverage requirements to nearby terrain and checking depth missed by sparse samples.

• Excluded Alfheim light-only sections from shadow terrain coverage counts.

• Removed AUSM's vanilla client packet-handler mixin, including packet-cancellation guards and chunk-triggered tile-entity reconstruction.

• Made AUSM explicitly client-only and disabled its coremod and mixin hooks on dedicated servers. Servers do not need AUSM installed.

• Removed the Better Portals server-world repair.