feat: implement item detail page and form components

- Created ItemForm component with fields for all metadata (priority, due date, tags, notes)
- Created ItemDetail component to display all item information
- Built /list/[id]/item/[itemId] page for viewing full item details
- Built /list/[id]/item/[itemId]/edit page for editing items
- Added form validation for item inputs (title required, length limits)
- Created DeleteItemButton and ToggleItemButton helper components
- Enhanced createItem action to support full metadata on creation
- Added getItem action to fetch individual items with list data

Requirements: 1.1, 1.2, 5.1, 5.2, 5.3, 5.4

.vscode/settings.json

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