Extend lists: per-item delete in edit form + hide checked items in widget

[pgarr]

Summary

• List edit form: Each item row in ListForm now has a trash icon button. Tapping it removes that item immediately from the form without affecting other items.
• Android widget: The home-screen widget now filters out checked items, showing only unchecked tasks. Widget checkbox taps still correctly toggle the right item in the database (original JSON indices are preserved).

Test plan

• Create a list with 3+ items → open edit screen → confirm trash buttons appear next to each item
• Delete a middle item → confirm it's removed without disturbing the others → save → confirm deletion persisted
• Add a list with some checked and unchecked items → place the widget → confirm only unchecked items appear
• Tap an unchecked item in the widget → confirm it disappears from the widget after refresh
• Reopen the app → confirm the tapped item is now checked (data integrity preserved)

🤖 Generated with Claude Code