Issues with new start page

[joschahenningsen]

This issue tracks problems we need to solve on the new start page before it can go live

• [x] #1025
• [x] #1023
• [x] #1020
• [x] #1021
• [x] #1022

Not important but perhaps nice/something for a follow up:

• [x] #1026
• [ ] Livestream thumbnails should look like vod thumbnails (this can be ignored until the worker overhaul)

[joschahenningsen]

@MatthiasReumann feel free to convert to issue -> self assign whatever you want to do, I'll take the rest if it makes sense :)

[joschahenningsen]

• [x] Access to course pages that are not allowed should redirect to login when not logged in or show a 403 page when logged in. e.g. https://live.rbg.tum.de/?year=2023&term=S&slug=ADLfP&view=3
• [x] The logo should be larger