Feat: add an endpoint that uses dir-go wasm to generate a proof.

[0xMugen]

This pull request introduces a new Go-based Groth16 proof generation feature for the SDK, including a custom React hook, integration and unit tests, development environment setup, and workspace configuration. The most important changes are grouped below by theme:

Go Proof Generation Feature

• Added the useGoProof React hook in react/src/useGoProof.ts, which loads a Go WASM prover, exposes a generateProof function, and manages prover state. This includes TypeScript interfaces for Groth16 proof structures and witness data. ([react/src/useGoProof.tsR1-R133](https://github.com/mistcash/sdk/pull/2/files#diff-1a693f65e9b66cd69559a4aaf723f5e598f28a56b022d43320c64292f4158989R1-R133))
• Exported the new useGoProof hook from react/src/index.ts for use in external projects. ([react/src/index.tsR2](https://github.com/mistcash/sdk/pull/2/files#diff-16ffa9feb0208f3a8b311e206274cc227173b52477e6bc8fda8c011c814cd613R2))

Testing

• Added a comprehensive integration test in react/tests/useGoProof.integration.test.js to validate real Groth16 proof generation using actual WASM and witness data. ([react/tests/useGoProof.integration.test.jsR1-R111](https://github.com/mistcash/sdk/pull/2/files#diff-55c78bee1b107d5e43ee712e1e89886297c9dd60147455c3e0af94b1bde75479R1-R111))
• Added a unit test suite in react/tests/useGoProof.test.tsx to mock and verify the behavior of the useGoProof hook, including error handling and state management. ([react/tests/useGoProof.test.tsxR1-R156](https://github.com/mistcash/sdk/pull/2/files#diff-a5796c69730677357dd399b64bee9d1b216170b4fad60f3d9ca88abb51d142aeR1-R156))

Development Environment & Workspace

• Introduced flake.nix to provide a reproducible Nix-based development environment with Node.js and pnpm for the SDK. ([flake.nixR1-R24](https://github.com/mistcash/sdk/pull/2/files#diff-206b9ce276ab5971a2489d75eb1b12999d4bf3843b7988cbe8d687cfde61dea0R1-R24))

Nix is niec of dependency management.

Testing Configuration

• Updated jest configuration. Tbh this is the only way I could get the testing to work. I'm not familiar with jest

[shramee]

Closing in favor of #3