Kotlin Expense Tracker Prototype

I want a small Expense Tracker written in Kotlin that lets me:

• Add expenses with category, amount, and date
• See the total spent at a glance
• Filter the list by category

I have no strong UI preference, so a clean console program is fine; however, if you prefer to build a simple UI, target mobile. When you implement persistence, store the data in Firestore or a comparable cloud option—local storage can remain a fallback only if time is tight.

Please keep the code modular and readable. Use data classes, lists or maps, and basic I/O where needed, and follow solid OOP practices.

Deliverables
• Complete, runnable Kotlin source with comments
• A quick demo video or GIF that shows the main flows working
• A brief README explaining setup, build, and any Firestore configuration

If you have sample Kotlin mini-projects, attach them so I can gauge your style.