test(backend): add error-envelope coverage matrix and fix e2e suite (… - #323

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4, actions/setup-node@v4, pnpm/action-setup@v2. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Unsafe assignment of an `any` value

Unsafe member access .authType on an `any` value

Unsafe member access .authType on an `any` value

Unsafe member access .user on an `any` value

Unsafe assignment of an `any` value

Unsafe member access .includes on an `any` value

Unsafe call of an `any` typed value

Unsafe member access .url on an `any` value

Unsafe member access .path on an `any` value