fix: code review fixes

- Fix hardcoded user path in webapps.nix (use homeDirectory)
- Normalize wallpapers option to use .enable suffix
- Remove duplicate FZF keybind declaration
- Update comments to match actual implementation

hosts/m3-hermes/configuration.nix

@@ -19,6 +19,7 @@
   environment.systemPackages = with pkgs; [
     neovim
     git
+    tea
     ghostty.terminfo
   ];