fix(config): use zoo-code-settings.json for settings export/import (#1177)

The settings export and import dialogs still defaulted to the legacy
"roo-code-settings.json" filename, as did the autoImportSettingsPath
example in the localized setting descriptions. Rename the default to
"zoo-code-settings.json" to match the Zoo Code branding.

This only changes the default filename suggested in the save/open
dialogs; existing files with any name can still be imported.