feature: lazy-load images where possible

Created by: cmeessen

Fixes #34 (closed)

Changes proposed in this pull request:

• Where possible, use NextJS <image/> component to enable automatic lazy loading
• the <image/> component is used in the Spotlight and the Upcoming section

How to test:

• observe network traffic when opening the page and confirm that spotlight image and the "upcoming" stock photo only load when being scrolled into view