143 small widget create a new category

[SuzGupta]

Closed issue #143

What it Does

This is part of the way toward creating a small widget that opens the New Category view (shows CategorySheetView). However, I need some help figuring out the deep linking part.

How I Tested

1. Add the widget in the simulator by searching for "Brain".
2. Pause to admire the not-too-bad layout.
3. Wince slightly when it does not open the expected view.

Notes

• IrrelevantCuteView.swift was a test view I was hoping to display on the way to debugging why I could not launch CategorySheetView. However, I stalled out earlier because onOpenURL does not seem to be called at all.

  Screenshot

• Add a screenshot of your new feature! OR show a screen recording of it in action

[SuzGupta]

What's changed:

• Moved onOpenURL into CategoryList. This now sets showingCategorySheet to true, displaying the New Category sheet view.
• After discussion with @baus8650, who helped with all of this, I ended up keeping the tags to identify the tabs in ContentView. This enables us to correctly return to the CategoryList view even if the app was previously in the Settings view when the widget was tapped.

The widget now works as expected.