feat: e on the status pane edits the config (#55)

`e` on the status pane (`0`) opens your config file, as in lazygit's status panel. The status footer shows it as `e edit config`. There's no global key. It opens the config the same way `e` opens a local file:
- inside nvim, in that nvim (lazysecrets quits);
- otherwise in `$VISUAL` or `$EDITOR`, coming back after;
- otherwise in the system's default app.

It opens the first config file: your own, also when `--config` layers several. A config that doesn't exist yet is created with a comment linking to its docs. Closing the editor says "restart lazysecrets to use it", since the config is read at startup.

Docs: keys.md (status pane) and config.md. Tested: the default app with a new config, nvim with an existing one left unchanged, the restart message, and the footer.

🤖 Generated with [Claude Code](https://claude.com/claude-code)
Reviewed-on: #55
Co-authored-by: Karl-Einar Bergstrøm <karl-einarb@outlook.com>

internal/ui/app/help.go

@@ -54,7 +54,8 @@ func (c contextHelp) ShortHelp() []key.Binding {
 	switch {
 	case c.focus == paneStatus:
 		details := key.NewBinding(key.WithKeys(k.Enter.Keys()...), key.WithHelp(k.Enter.Help().Key, "details"))
-		return append(b, details, k.Update, k.Help, k.Quit)
+		config := key.NewBinding(key.WithKeys(k.Edit.Keys()...), key.WithHelp(k.Edit.Help().Key, "edit config"))
+		return append(b, details, config, k.Update, k.Help, k.Quit)
 	case c.focus == paneDetail && c.account && c.of == paneStatus:
 		open := key.NewBinding(key.WithKeys(k.Open.Keys()...), key.WithHelp(k.Open.Help().Key, "open link"))
 		return append(b, k.Up, k.Down, copyField, open, k.Edit, k.Filter, k.Help, k.Quit)