Remove filesize; use local formatter for upload progress

[FenPWysocki]

Summary

Replace filesize with a tiny in-repo utility formatBytesObject() to format bytes and keep aligned units in upload progress.

Changes

• Added formatBytes.ts exporting formatBytesObject
• Removed filesize from package.json

Behavior

Uses SI units (B, kB, MB, …) with base 1000 and 1-decimal rounding; preserves aligned-unit display (e.g., “1.2/3.4 MB”). No locale or bits support.

Impact

Smaller dependency footprint; tiny risk of minor formatting differences vs filesize on edge cases.

Verification

Local typecheck and build pass; no runtime logic changed beyond formatting. Optional: run tests (npm test).