Replace the `default_window` string field with a `View` enum throughout
the
application. Introduce a new keybinding module providing `Action`,
`KeyBinding` structs and helper functions, and integrate a keybindings
widget
into the main menu. Update the CLI to accept a `View` value enum and
adjust
imports and event handling accordingly. Add a release profile in
`Cargo.toml` with LTO, single codegen unit, higher optimisation level
and
binary stripping for smaller, faster builds.