Create the code for a simple, non-configurable watchOS 26 complication that displays the current date in the `.accessoryRectangular` family.

The code must include:
1. A `TimelineProvider` to generate the timeline entries.
2. A `TimelineEntry` struct.
3. The main `Widget` struct.
4. A SwiftUI view for the complication's appearance.

Ensure the code correctly uses the modern WidgetKit framework.