perf(coworld): enable LTO for Linux game images

[macromackie]

Summary

Enabling Nim's -d:lto for the shared Linux Coworld game-image build used by GotA, LvD, CTA, and AWM. The flag lets GCC optimize across the generated C files using the existing pinned compiler and release settings.

Eight controlled games on approved source 02eda3d formed four matched baseline/LTO pairs in one Modal task. Native elapsed time fell 11.14–14.78% (median 13.35%), with exact replay and result parity. That small sample covers two seeds and BASIC/neural rosters; it does not establish a gain for the currently deployed binary. This branch includes the subsequently merged target-filter optimization.

Game publication and deployment remain separate release decisions.

Manual Tests

• Built all four actual Linux/amd64 images from the changed Dockerfile.
• Ran the resulting GotA image locally on BASIC and neural fixtures. Replay and result hashes exactly matched the approved-source experiment for seed 2026 and map seed 54.
• Existing all-game determinism, GotA lockstep, and AWM match/replay suites passed with LTO inside the Docker compiler image.

[Prepared with Codex]