fix: usd precision

[helciofranco]

• Closes Fix value in USD calculation #1862
• Closes FE-1491

Summary

Fix USD calculation and add unit tests to ensure we'll not face it again.

📷 Demo

Checklist

• I've added error handling for all actions/requests, and verified how this error will show on UI. (or there was no error handling)
• I've reviewed all the copy changed/added in this PR, using AI if needed. (or there was no copy changes)
• I've included the reference to the issues being closed from Github and/or Linear (or there was no issues)
• I've changed the Docs to reflect my changes (or it was not needed)
• I've put docs links where it may be helpful (or it was not needed)
• I checked the resulting UI both in Light and Dark mode (or no UI changes were made)
• I reviewed the entire PR myself (preferably, on GH UI)

[nelitow]

All use cases I tried worked perfectly. Tested around 10 different TXs. Assets, asset sums and extreme rates.
Audit fix missing