refactor(home-manager): refine CLI feature configurations

- Add direnv module with nix-direnv integration, replacing manual hook
- Disable starship's add_newline for more compact prompt
- Clean up comments across CLI features for better readability

nixos/fuchsia/configuration.nix

@@ -27,8 +27,6 @@
   # Configure programs
   programs = {
     zsh.enable = true;
-    # Load and unload environment variables
-    direnv.enable = true;
     # Android debug bridge: communicate with devices
     adb.enable = true;
   };