[Extern API] Match Budget enum to google maps price level

[eclipse-909]

Description

Our budget enum needs to correspond to the price level enum we get from google maps. In the events table and Event struct, it's stored as an int. The accounts table and Account struct need to be updated to match that.

Acceptance Criteria

• accounts table uses INTEGER for budget
• Account models use i32/number instead of BudgetBucket enum
• BudgetBucket enum is deleted everywhere in codebase (sql type, rust enum, typescript enum)
• In frontend, budget dropdown options can be displayed with a switch case over the number or something

Developer Notes

• google maps docs for price level