Add features related to budgeting

[anqichen9856]

As a non-money minded person who wants to be better at tracking my expenses, I want the app to let me have some way of keeping a budget.

Specifically, I can:

1. [Periodic Budget] Set periodic budgets so that I can discipline my spendings.
2. [Categorical Budget] Set categorical budgets so that exceptional expenses (e.g. healthcare or sponsored expenses) are not tracked under default budget to prevent confusion.
3. [Reminders] Receive warnings when I’m close to my budget so that I can adjust my spending.
4. [Warnings] Get a clear indication of when I am close to or exceeding my budget.
5. [Tips] Suggest some budgeting tips for me.

[anqichen9856]

Periodic budgets

[anqichen9856]

Categorical budgets