Add Node.js bindings using N-API

[google-labs-jules]

This PR adds Node.js bindings to the MNN project. It introduces a new nodemnn package that uses node-addon-api and cmake-js to expose MNN's C++ API to Node.js.

Key features:

• Interpreter: Create interpreters from model files.
• Session: Create and run inference sessions with configurable backend and thread count.
• Tensor: Create tensors, access/modify data (Float32 support), and copy data between host and device tensors to handle layout differences correctly.

The bindings are designed to mirror the structure of the existing Python bindings. A functional test is included which loads mobilenet-v1-1.0.mnn and performs a dummy inference pass.

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PR created automatically by Jules for task 6058395546264760444 started by @Juude

[google-labs-jules]

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