chore: development environment setup + fix corrupted seed JSON

[EnglandTong]

Summary

Sets up the development environment for Cursor Cloud agents and fixes a data corruption issue that prevented the API from starting.

Changes

• Fix modules/math-algebra/seeds/B1.json: Repaired a corrupted question entry that contained a literal control character (newline inside JSON string), which caused JSON.parse() to fail in moduleLoader.ts and prevented the API server from starting.
• Add AGENTS.md: Documents Cursor Cloud specific development instructions including service overview, MongoDB startup, build order gotchas, and standard commands reference.

Verification

All checks pass with the fix applied:

• pnpm typecheck — all 6 packages clean
• pnpm lint — all lint-configured packages pass
• pnpm test — 125 tests pass (53 algorithm + 18 validation + 54 API)
• pnpm build — full production build succeeds
• API dev server starts and responds to health checks
• Web dev server (Vite) serves the React frontend
• Full learning loop verified: register user → start diagnostic → get question → submit answer → receive adaptive feedback

dev_environment_verification.log

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