Add minimal smoke tests (Hardhat + Frontend)

[LuminaEnvision]

A minimal test layer is needed before the next deploy.
Expected work: Create Hardhat tests for the approval → NFT mint → reward flow. Create a manual smoke test list for the frontend. Optional: Set up a GitHub Action to run tests.
Why this matters: Prevents regressions and deployment surprises.

[BeRegen]

Backend stabilization update.

The complete test suite (104 passing) now provides a reliable foundation for smoke testing. During the refactor:

✔ RewardManager tests fully stabilized
✔ Submission logic verified under viem
✔ Storage, Token, NFT, and POI sequences work end-to-end
✔ Test environment cleaned and standardized

Next steps for this issue:
• Add one end-to-end Hardhat smoke test:

• submit → approve → mint NFT → reward → claim
  • Add one frontend smoke script (Node/Next.js)
  • Validate environment variables + RPC + wallet connections

This issue can now progress with a stable backend baseline.

[BeRegen]

Status update after frontend stabilization.

The frontend is now fully compiling, type-safe, and stable across all core flows:
✔ Cleanup submission
✔ Verification
✔ Claim
✔ Profile
✔ Leaderboard

Previous instability (type mismatches, placeholder contract stubs, missing exports)
made automated smoke tests unreliable.

With the UI now stable and aligned to the current contract surface,
we are unblocked to add:

• Minimal frontend smoke tests
• Basic Hardhat deployment + interaction tests

Tests were intentionally deferred until core behavior stopped changing.

Issue remains open and ready for implementation.