Add log view UI with transaction entry form

Expense/Income toggle, amount entry, currency dropdown, category
dropdown (filtered by transaction type), date picker with calendar
popover, optional note field, save button, and recent transactions
placeholder section.

outlay-gtk/src/main.rs

@@ -1,3 +1,4 @@
+mod log_view;
 mod window;
 
 use adw::prelude::*;