chore: stack upgrade

[hieu-w]

Motivation and Context

Modernize the web3auth-backend Node SDK by upgrading dependencies, migrating the test framework, replacing ethers with viem, removing Node.js Buffer polyfills, and adding CI and code ownership configuration.

Jira Link:
https://consensyssoftware.atlassian.net/browse/EMBED-29

Description

Test framework migration: Mocha + Chai → Vitest

• Removed .mocharc.json, babel.config.js, and test/setup.mjs
• Added vitest.config.mts with verbose reporter and istanbul coverage
• Rewrote test assertions from Chai (expect(...).to.equal(...)) to Vitest (expect(...).toBe(...))

ethers → viem

• Replaced ethers (Wallet, JsonRpcProvider) with viem (createWalletClient, privateKeyToAccount, http)
• Updated WalletResult EIP155 signer type from Wallet to WalletClient

Buffer polyfill removal

• Buffer.from(..., "base64") → Uint8Array.from(atob(...), (c) => c.charCodeAt(0))
• Buffer.from(..., "utf8") → new TextEncoder().encode(...)

Utility update

• safeatob → base64toJSON from @web3auth/auth

Dependency version bumps

• Bumped all @toruslabs/*, @web3auth/*, @solana/*, @segment/* to latest majors
• Removed Babel-related packages, mocha, chai, tsx, tsconfig-paths
• Added vitest, @toruslabs/torus-scripts
• Node engine: >=20.x → >=22.x; npm: >=9.x → >=10.x
• Build script: rimraf dist/ && tsc → torus-scripts build
• Lint script: eslint --fix 'src/**/*.ts' → torus-scripts lint src test

CI & CODEOWNERS

• Added .github/workflows/ci.yml (Build, Test & Lint on push, Node 24.x)
• Added .github/CODEOWNERS with @torusresearch/Admins fallback and @torusresearch/Web3Auth-Product for source/test

ESLint config

• Removed mocha/no-setup-in-describe rule
• Added import/no-extraneous-dependencies: off for test and config files

How has this been tested?

• Migrated existing integration tests to Vitest and verified they pass against live Torus nodes
• Tests cover: EIP155 wallet creation with signer, aggregate login with signer, and Solana login with TransactionSigner
• Build and lint verified locally via npm run build and npm run lint

Screenshots (if appropriate):

N/A

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project. (run lint)
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.
• My code requires a db migration.

---

Note

Medium Risk
Moderate risk due to CI/build pipeline and Node version baseline changes, which can surface environment-specific failures across packages. No runtime/auth logic is changed in this diff, but the new JWT_PRIVATE_KEY secret requirement can break tests if not configured.

Overview
Adds repo-level automation and ownership controls. Introduces .github/workflows/ci.yml to run build, lint, and test on push using Node 24.x, passing JWT_PRIVATE_KEY from GitHub secrets, and adds a CODEOWNERS policy with admin/product ownership.

Updates local/tooling configs. Adds .env.example for test setup, bumps .nvmrc to >=24.x, removes legacy .mocharc.json and babel.config.js, tweaks eslint.config.mjs to drop Mocha-specific rules and disable import/no-extraneous-dependencies for tests/config, and slightly tightens .gitignore/.npmignore cache entries.

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[hieu-w]

w3a-backend.cursor_code_review_against_main_branch.md

[chaitanyapotti]

should be web3auth

[hieu-w]

I've fix this, however team @Web3auth/Web3Auth-Admins not existed in Web3auth org, so we need create it.

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[chaitanyapotti]

you need to use the lerna based folder structure