Switch to pnpm package manager for frontend

[ckcherry23]

What feature(s) would you like to see in RepoSense

Switch our frontend package manager from npm to pnpm for speed and space efficiency. With our recent move to Vite in #2178, we can continue optimizing our frontend tools for better developer experience and performance.

Is the feature request related to a problem?

npm uses flattened node_modules which makes it difficult to debug issues related to using implicit dependencies. pnpm on the other hand uses hard links and symlinks to a global content-addressable store with a tree-like dependency structure. This makes it impossible to use implicit dependencies in code. Moreover, this allows a dependency to only be saved once on the disk and reused across multiple projects. This in turn also boosts installation speeds. See more about npm vs pnpm.

If possible, describe the solution

Here's a migration guide for npm to pnpm. Note that the workspaces section may not be relevant as we currently do not use npm to manage a monorepo.

For this migration, the following files may need to be updated:

• Gradle build file
• Frontend's package.json
• CI/CD scripts
• User Guide
• Developer Guide

If applicable, describe alternatives you've considered

Yarn v4 may also be an improvement over npm, and is a viable option to consider.