Performance issues

[patrick11514]

• The images in gallery currently (in list /[[lang]]/gallery and in specific article /[[lang]]/gallery/[id]) block main app, when loading, so user can't navigate back, or click links, because app is frozen, until all images load (so this needs to fix) and also the images should load lazy, only when person scrolls to them
• Cache images, for images /images/[id]/+server.ts we need to add caching headers, for quite long, beacuse the image will not be changed. Also we should send headers early, before we even load the image content, so the headers came asap
• Optimize the way of loading images, because currently it takes ages to load them (/images/[id]/+server.ts)