[dgant]

Game.isWalkable(int, int) now checks walk-grid bounds and reads the walkability array directly, avoiding construction of a WalkPosition. The WalkPosition overload delegates to the integer overload so both use the same bounds checks.

In-map results are preserved. As a correctness consequence of comparing coordinates directly with the map bounds, both overloads consistently return false for out-of-range coordinates, including very large positive values.

Validation:

• Full Maven package on Windows Java 8u171 x86: all 44 tests pass on 2068443, with zero failures, errors, or skips.
• Both overloads are checked against the fixture's map data across every walk tile, including walkable and blocked terrain.
• Both overloads reject negative coordinates, the map boundary, and very large positive coordinates.
• The preceding implementation at cd27cd8 completed a full PurpleWave game versus Stardust on Fighting Spirit: 11,875 frames, normal defeat, no crash or timeout. That game predates this overload-delegation cleanup.