Retype CoordEntry fields from raw i32 to named Fixed center_x/y and
center_x_target/y_target. Extend viewport_coords array to 5 entries to
cover the init spill. Retype init_game_state_level_bounds param from
*mut u8 to *mut DDGame, removing all raw pointer arithmetic.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
refactor: rename TeamArenaState to TeamArena, use raw pointers for soundness