Fix React Expense Tracker Bugs

I’ve built a small React-based expense tracker to manage costs for my candle-making business. It’s a single-page app that stores everything in localStorage—about 800 lines of code in a private GitHub repo I’ll share once we start. Most of it works, but three glitches are blocking me:

• The running total is treating numbers as strings, so $12.50 and $30 show up as “12.5030” instead of $42.50.
• When I filter by month and delete an expense, the wrong entry disappears.
• Any expense dated on the 1st of a month ends up listed under the previous month.

I need clean, well-commented fixes that leave the overall structure intact—no major rewrites, just solid JavaScript and React troubleshooting. Please commit your changes to a feature branch, include a short note or PR description outlining what you touched, and verify everything works smoothly across Chrome, Safari, and mobile browsers.

Timeline is tight: I have to send numbers to my accountant in 2–3 days, so I’ll be reviewing PRs quickly. If you’re comfortable debugging React components that rely on hooks and localStorage (no backend), I’m ready to give repo access right away.