chore: update browser, theme, and locale configurations

- Replace Librewolf with Firefox as the backup browser
- Update default and extra locales to en_US.UTF-8 and de_DE.UTF-8 respectively
- Change theme fetch setting from 'none' to 'fastfetch' and update wallpaper
- Minor formatting cleanup in THEMES.md

home/programs/group/basic-apps.nix

@@ -11,7 +11,7 @@
 
     ticktick # Todo app
     onlyoffice-desktopeditors # Office suite
-    librewolf # Backup browser
+    firefox # Backup browser
 
     # I love TUIs
     caligula # User-friendly, lightweight TUI for disk imaging (ISO, USB BOOT)
@@ -33,28 +33,9 @@
     imagemagick # Image manipulation tool
     chafa # Image to ANSI/Unicode converter and more.
 
-		/*
-		Disabled
-		resources # Ressource monitor
-
-		textpieces # Manipulate texts
-		gnome-clocks # Clocks app
-    gnome-text-editor # Basic graphic text editor
-		pinta # Image editor
-		switcheroo # Convert images between different formats
-		signal-desktop # Messaging app
-
-		blanket # Listen to different sounds
-		gh # GitHub
-    gh-dash # A terminal dashboard for GitHub
-    figlet # Transform text into ASCII art
-		pkgs-nur-hadi.sheets # Terminal based spreadsheet tool
-		slides # A terminal-based presentation tool that allows you to create and deliver presentations directly from the command line
-		*/
-
   ])
 
 	++ (with pkgs; [
-		vencord # Vencord Discord Mod
+		vesktop # Vencord Discord Mod
 	]);
 }