Firefox & various package updates

[tsandrini]

Firefox & various package updates

Overview

Replace treestyle-tab (whose installation doesn't currently work nonetheless) with sidebery addon. Also add a few new badges to README.md + switched from using flake packages to nixpkgs package version instead due to better cache support.

Testing

Dependencies (flake inputs)

Removed github:viperML/nh input (replaced with nh from nixpkgs instead).

Screenshots

Checklist

• I have tested the relevant changes locally.
• I have checked that nix flake check --impure passes.
• I have ensured my commits follow the project's conventional commits guidelines.
• I have checked that the changes follow a linear history.
• (If applicable) I have commented any relevant parts of my code.
• (If applicable) I have added appropriate unit/feature tests.
• (If applicable) I have updated the documentation accordingly (in English).

Additional Notes