feat: Zero-Knowledge Anonymous Provider Staking & Shielded Reputation Proofs (#427)

[devJaja]

Summary

Implements a zero-knowledge shielded staking pool that allows providers to deposit collateral and verify minimum stake compliance via zk-SNARK proofs, without revealing their public wallet address.

Changes

Database Layer

• 032_add_shielded_provider_staking.sql: Creates shielded_stake_commitments and shielded_provider_nullifiers tables with indexes

Backend

• shielded-staking.ts: POST /provider/shielded-stake, POST /provider/shielded-stake/verify, GET status and merkle-root endpoints
• crypto.ts: Added generateShieldedCommitment() and verifyShieldedCommitment() helpers

Concurrency Safety

• Uses SELECT FOR UPDATE on nullifiers to prevent race-condition double-spending during concurrent verification requests

Smart Contracts

• lib.rs: Registered shielded_staking module in the reputation contract

Frontend

• ShieldedStakingModal.tsx: React component with multi-step flow (generate proof, deposit, verify) using Catppuccin Mocha styling

Tests

• 9 unit tests covering: valid deposit, duplicate commitment (409), insufficient stake (400), ZK proof verification, nullifier double-spend prevention (409), invalid proof (422), commitment status, merkle root queries

Acceptance Criteria

• Provider can deposit collateral into shielded pool without revealing public wallet address
• ZK proof verification prevents nullifier double-spending
• SELECT FOR UPDATE prevents concurrent race conditions on nullifier insertion
• Invalid proofs are rejected with 422 status
• All 57 existing API test files pass (526 tests, 0 new regressions)

Closes #427

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[jotel-dev]

Hey @devJaja — nice work on the ZK anonymous provider staking & shielded reputation proofs feature! 👏 Contracts CI and node build are both green, but before we can merge there are a couple of things to sort out:

Merge conflicts in apps/api/src/app.ts, locales/en.json, and locales/es.json — can you resolve these against main?
Vercel deploys are failing with "Authorization required to deploy" — can you check the Vercel project permissions/env on your end? Let me know if you need access sorted out on our side.

Ping me once those are resolved and I'll get this reviewed and merged. 🙏

[vercel]

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Project	Deployment	Actions	Updated (UTC)
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