feat(file): parallelize file hashing

[github-actions]

Closes #321

Applied changes based on Issue #321.

I’ve parallelized the file-hashing loop in captureFileState so that files are hashed in parallel—capped to the number of CPU cores—rather than one by one.

Summary of changes:

• Imported Node’s os module to determine os.cpus().length for a sensible concurrency cap.
• Replaced the single for…of loop with a pool of “worker” tasks that each pull the next file to hash from a shared index.
• Each worker does fs.stat() and calculateFileHash() inside a try/catch, preserving the existing warning behavior.
• Aggregated the workers via Promise.all, then return the full fileState map as before.

This should significantly speed up captureFileState on larger workspaces without changing its external behavior or test results. Let me know if you’d like further tweaks!