feat: local engine - symlink bundled variants

[louis-jan]

Describe Your Changes

Currently, Jan packages all the available engines into the compressed app resource folder. E.g. on MacOS, it's inside Jan.app > Contents > Resources > app.asar.unpacked > shared. Since this folder is read-only, there's no way to download, install, or update the engine variant in the directory.

Now Jan symlinks all available bundled variant versions to Jan Data Folder, so that cortex.cpp server can function consistently without issue about writing permissions. The engine_path environment variable is set so that cortex.cpp can remove the complex implementation of handling the engine environment.

This PR also experimented with rolldown.rs to compile extensions much faster.

Fixes Issues

• Closes feat: pre-packaged engine variants and installation directory #4337

Changes made

This pull request includes significant updates to the engine-management-extension package. The changes involve switching the build system, adding new dependencies, introducing a custom error class, updating the main extension logic, and refactoring tests.

Build System and Dependencies:

• package.json: Replaced tsc and webpack with rolldown for the build process, added @rollup/plugin-replace and rolldown as devDependencies, and included cpu-instructions as a dependency.
• rolldown.config.js: Added a new configuration file for rolldown to define build settings and plugins.

Custom Error Handling:

• src/error.ts: Introduced a new EngineError class to handle specific engine-related errors.

Main Extension Logic:

• src/index.ts: Updated the main extension logic to handle symlinking engines, running health checks, and comparing engine versions using the new EngineError class. [1] [2] [3]

Refactoring Tests:

• src/node/index.test.ts: Refactored and renamed tests to align with the new structure and methods in the engine-management-extension. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15]

File Renaming and Refactoring:

• src/node/index.ts: Renamed from execute.ts and refactored to include new imports and remove unused functions. [1] [2]

[github-actions]

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