Refactor to View enum and add keybindings

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.

Cargo.toml

@@ -3,6 +3,12 @@ name = "war_in_tunnels"
 version = "0.1.0"
 edition = "2024"
 
+[profile.release]
+codegen-units = 1
+lto = true
+opt-level = 3
+strip = true
+
 [dependencies]
 clap = { version = "4.5.53", features = ["derive"] }
 ratatui = "0.30.0"