feat: polish game HUD scoring and results

COLLABORATION_RULES.md

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+# Collaboration Rules
+
+When changing code in this project, Codex and Claude Code should use a mutual review gate before proceeding.
+
+## Code Change Gate
+
+1. Before editing code, state the intended change and expected impact.
+2. Share feedback between Codex and Claude Code when both are active.
+3. Score the proposed change out of 100 based on:
+   - Correctness
+   - Scope control
+   - Risk to current Unity scenes and runtime behavior
+   - Maintainability
+   - Test or verification plan
+4. Proceed only when the agreed score is 80 or higher.
+5. If the score is below 80, revise the approach first.
+
+## Current User Preference
+
+For now, focus on polishing the Unity Game scene. Do not change code unless the review gate above is satisfied.