feat(ui): render layout, tabs, panes, popups, and status bar
- ui/mod.rs: AppView struct, Focus/Popup/NetworkStatus enums, draw() layout function
- Top-Tabs + Bottom-Split layout (50/50 left/right)
- TabsBar: list selector with highlight on active
- TaskListPane: checkbox + title + due date per task
- DetailPane: title, status, due, notes of selected task
- InputPopup: centered modal with cursor
- DatePickerPopup: date/time edit modal with instructions
- ConfirmDeletePopup: confirmation dialog
- DeviceAuthPopup: OAuth URL + code display
- StatusBar: ONLINE/OFFLINE/SYNCING with color coding
Ruben Rosario
efc3c1c84c