feat: enhance Fish shell config with fzf bindings, Fisher auto-update, and native Linux browser

- Add fzf.fish keybinding customization (remap variables, preserve Atuin history)
- Add Fisher plugin auto-update hook for chezmoi apply
- Set Vivaldi as default browser on native Linux
- Improve commit-staged command instructions
- Add Kitty font size configuration

home/.chezmoitemplates/scripts/commonrc.sh.tmpl

@@ -170,6 +170,10 @@ wt() {
 
 # SSH key management (keychain loads keys once per WSL session)
 eval `keychain --quiet --eval --agents ssh ~/.ssh/id_rsa`
+{{- else }}
+
+# Native Linux browser (use Vivaldi)
+export BROWSER=vivaldi-stable
 {{ end }}
 
 # atuin (magical shell history with sync)