Unity foundation and playable scene checkpoint

[YIFNEN]

Summary

• preserve Unity 2022.3.60f1 project hygiene, agent contracts, canonical asset manifest, and the GUID-preserving Monkey/CoolDryer baseline
• establish GameSession Core/Data definitions with guarded phase/day transitions and TDD coverage
• add concise Unity validation/test automation that rejects missing scenes, references, zero discovered tests, temporary PostBox content, and invalid Foundation data
• route the loading scene's mouse/keyboard input to the actual isometric scene
• stabilize the maintained legacy combat lifecycle and checkpoint its focused EditMode/PlayMode tests
• restore positive CoolDryer damage values and checkpoint the playable isometric scene without the temporary PostBox prefab/material

Current asset baseline

• 101 included sheets plus 22 canonical single sprites
• Player Walk B05/B06 excluded as historical
• Bear and BearHeavy retained as distinct roles
• CommonSoldier and Monkey retained

Verification

• exact clean gameplay tip: 647375f774669b396c2faab616ffd953acdeefd7
• current PR tip: 48b257cd758d4a86fd19e94ad2acc1faf865691e (gameplay tip plus README-only origin/main merge)
• PASS unity-editmode total=19 passed=19 failed=0
• PASS unity-playmode total=3 passed=3 failed=0
• PASS unity-validate
• PASS unity-repo-hygiene files=2471 assets=2421 manifest=125
• GitHub unity-repo-hygiene run 5: success
• temporary PostBox prefab/material GUID references in the committed playable scene: 0
• independent checkpoint code review: approved

Scope boundary

• WebGL is intentionally not added on this Foundation branch.
• The OpenAI Game Builders submission work will start from this verified checkpoint on an isolated codex/openaigame2026 worktree.
• Raw/intermediate art, prototype Assets/_Project/Scenes/Game.unity, unsafe one-shot migration code, generated builds, and unrelated dirty legacy changes remain excluded.