Read and write files in an E2B sandbox filesystem from the SDK

Documented steps

1. Write a single file: Python `sandbox.files.write('/path/to/file', 'content')`, JS `await sandbox.files.write('/path/to/file', 'content')` (https://e2b.dev/docs/filesystem/read-write)
2. Write multiple files in one call: Python uses the separate method `sandbox.files.write_files([{"path": ..., "data": ...}])`; JS overloads the same method with an array `await sandbox.files.write([{ path, data }])`
3. Read a file back: `sandbox.files.read('/path/to/file')` in both SDKs
4. Upload local inputs by writing their contents into the sandbox before running code; download outputs by reading them after execution (https://e2b.dev/docs/quickstart/upload-download-files)