- Use `std.meta.fieldNames` for the save mode prompt.
- Update terminal prompt functions to accept null-terminated strings.
- Respect the resolved save mode in `synthesizeSave`.
Integrates isocline's top and bottom bar APIs to display the active
provider, model, and shortcut hints. Updates the status bar on
terminal resize and mode switches.
Extracts provider and model settings logic from `Agent.zig` into a new
`settings.zig` module. Replaces custom UTF-8 truncation logic with
`truncateUtf8` from `string.zig`. Also updates the `zenai` dependency.
