Show achievements when live milestones are met

[bashmohandes]

Summary

• add rate-limited, server-validated achievement checkpoints for irrevocable in-game milestones
• notify Tetris and local Battle Tanks achievements as their conditions are met while preserving end-result fallback and deduplication
• keep live toasts clear of mobile controls and document/test the trust boundary

Verification

• node --test (331 passed)
• full package syntax-check command run directly with node --check (passed)
• node --test tests/achievements.test.js tests/shared-game-assets.test.js (26 passed after final edits)
• git diff --check
• browser verification at desktop and 390x844 viewports

Note: npm itself is broken in this environment because its global npm-cli.js is missing, so the package scripts were executed directly with Node.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-03T23:31:53.436037Z	ab9307f	PR opened
🔒 Security Review	✅ Completed 2026-09-03T23:32:59.239873Z	ab9307f	PR opened

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[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: ab9307fd81

ℹ️ About Codex in GitHub

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