Fix missing star texture in Target eval

[Battleplus]

Summary

• point the Target renderer at the existing resources/onlyfish/star.png texture
• remove the missing-texture warning and restore visible goal markers during evaluation

Fixes #602.

Validation

• Confirmed every LoadTexture path in ocean/target/target.h resolves to an existing file.
• Decoded resources/onlyfish/star.png successfully as a 128x128 PNG.
• Compiled the standalone Target environment against the bundled raylib 5.5 library on Ubuntu 24.04 (WSL) using GCC.
• git diff --check passes.