Updates to Balance and Signal for new Signal Rules flows. Also updates dependencies and Plaid client libraries

[phoenixy1]

I ended up removing /accounts/balance/get and then later putting it back, and including both ways of calling balance in the quickstart. I think hopefully it's clear.

This PR was vibe-coded with my good friend Claude.

Contains a few fixes:

• Updates Plaid client libraries to latest versions
• Updates dependencies to resolve security warnings
• Other misc fixes to resolve dependency-related warnings
• Updates Signal API call to use a ruleset key and show ruleset evaluation results, as well as replacing some less-relevant /deprecated results like risk tier with results that are more relevant to Balance, like...balance
• Updates .env.example file to provide better instructions and be more appropriate for Fuse
• Fixes bug in which calling /signal/evaluate twice would result in a duplicate transaction error because the transaction_id was the same every time

[ToddKerpelman]

Approved with a suggestion!

[ToddKerpelman]

Any? Boo...

[ToddKerpelman]

Okay, I fixed this in a commit