First 2024 blog post and general cleanup

[ahoneybun]

This adds the NixOS COSMIC post and cleans up older content from the original Cass fork.

[github-actions]

Images automagically compressed by Calibre's image-actions ✨

Compression reduced images by 13.4%, saving 99.25 KB.

Filename	Before	After	Improvement	Visual comparison
images/blog/mobile-linux-phosh/gnome-software_homepage.png	187.86 KB	185.82 KB	-1.1%	View diff
images/blog/mobile-linux-phosh/gnome-software_installed.png	108.76 KB	81.54 KB	-25.0%	View diff
images/blog/mobile-linux-phosh/gnome-software_listing.png	134.69 KB	121.45 KB	-9.8%	View diff
images/blog/mobile-linux-phosh/gnome-software_up-to-date.png	122.04 KB	115.44 KB	-5.4%	View diff
images/blog/mobile-linux-phosh/settings_about.png	83.43 KB	62.38 KB	-25.2%	View diff
images/blog/NixOS-COSMIC/NixOS-COSMIC-running.png	70.68 KB	47.69 KB	-32.5%	View diff
images/blog/NixOS-Nginx/linode-domains.png	35.69 KB	29.58 KB	-17.1%	View diff

71 images did not require optimisation.