Add a image place holder in the widget v2

[sahalali]

Please add a default placeholder image for event listings and in the event details page if no image is available. Use a grey image; confirm with Sooraj if necessary.

To improve user experience, display a skeleton image while the actual image is loading, as the current layout jumps if the image takes time to load.

When no image is present, the layout appears visually unappealing, as shown in the attached screenshot.