QuickJS Binary Source Update

1. Context

The current quickjs-ng runtime is proving too slow for our needs. We need to switch to the original QuickJS runtime provided by Bellard.

Base URL: https://bellard.org/quickjs/binary_releases/
Versioning: Use LATEST.json at the base URL to find the latest version and filename.
- Format: {"version":"2024-01-13","files":{"quickjs-win-x86_64.zip":"quickjs-win-x86_64-2024-01-13.zip", ...}}
Target Files:
- Windows: Look for key quickjs-win-x86_64.zip.
- macOS: Look for key quickjs-cosmo-x86_64.zip (Cosmo builds are generally portable). Wait, need to confirm if macos specific builds exist or if cosmo is the intended one for unix-like.
- Correction: Bellard's page lists quickjs-macos-x86_64.zip? Let's check LATEST.json first. Assuming quickjs-cosmo might be Linux/Universal. Let's fetch LATEST.json to be sure.

src-tauri/src/binary_manager.rs:
- Update QJS_REPO_URL to https://bellard.org/quickjs/binary_releases.
- Add logic to fetch LATEST.json first.
- Parse the JSON to get the actual filename for the current OS.
- Download the ZIP file.
- Extract the binary (qjs.exe or qjs) from the ZIP.
- Rename it to our internal standard (quickjs.exe / quickjs).