fix: use file instead of in-memory buffer for download

[pepperoni505]

https://app.clickup.com/t/2628431/SIMDEV-542

[Copilot]

Pull Request Overview

This PR updates the download process by switching from an in-memory buffer to a file-based approach to reduce memory usage during downloads.

• Updated fs and io imports to use File and BufReader instead of Cursor.
• Introduced a constant (DOWNLOAD_TEMP_FILE_PATH) to store the temporary download file and modified the download logic accordingly.
• Adjusted extraction to load the zip archive from the file.

Comments suppressed due to low confidence (1)

src/wasm/src/funcs.rs:28

• [nitpick] Consider reviewing the file path for cross-platform compatibility; using Path::new or platform-specific path delimiters may prevent issues on non-Windows environments if applicable.

const DOWNLOAD_TEMP_FILE_PATH: &str = "\work/ng_download.temp";

[SkySails]

Seems to work as advertised! The memory usage stays put, and each chunk is successfully flushed to the temporary file. I manually throttled my internet connection to 300 KB/s to test this and had one download take over 2 minutes, which means that it would normally have failed (without chunking).

Screenshot shows mid download with the first chunks having been flushed to the file already, while the memory remains stable.

[navigraph-bot]

Task linked: SIMDEV-542 Have download/extraction buffers go to disk for interface