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

docs/THEMES.md

@@ -1,17 +1,17 @@
-# Themes
-
-Themes are defined in `themes`. Those themes define the colors, fonts, icons, etc, used by Hyprland and the apps/programs installed.
-You can change the selected theme by changing the import statement of your host's variables.nix file.
-
-## Create your theme
-
-Create a copy of one of the existing themes and change the variables.
-Wallpapers are loaded from the [hadi's awesome-wallpapers](https://github.com/anotherhadi/awesome-wallpapers) repo.
-
-## Gallery
-
-### Rose-pine
-
-![Home](../.github/assets/rose-pine/home.png)
-![Flake & Spotify](../.github/assets/rose-pine/flake-spotify.png)
-![Browser and notification center](../.github/assets/rose-pine/browser-and-notifications.png)
+# Themes
+
+Themes are defined in `themes`. Those themes define the colors, fonts, icons, etc, used by Hyprland and the apps/programs installed.
+You can change the selected theme by changing the import statement of your host's variables.nix file.
+
+## Create your theme
+
+Create a copy of one of the existing themes and change the variables.
+Wallpapers are loaded from the [hadi's awesome-wallpapers](https://github.com/anotherhadi/awesome-wallpapers) repo.
+
+## Gallery
+
+### Rose-pine
+
+![Home](../.github/assets/rose-pine/home.png)
+![Flake & Spotify](../.github/assets/rose-pine/flake-spotify.png)
+![Browser and notification center](../.github/assets/rose-pine/browser-and-notifications.png)