Align shell builder APIs and complete public authoring docs

[zcourts]

Fission applications can now seed the same prepared Env on Desktop, Mobile, Web, and Terminal. That makes translation and design-system setup portable instead of forcing Web apps to smuggle bundles through with_sync_env. Browser islands now retain the complete environment too, and can synchronize locale or theme from their own state before each build.\n\nA Web app can use the same setup as native:\n\nrust\nWebApp::<AppState, _>::new(App)\n .with_env(create_env()?)\n .with_design_system::<AppDesignSystem>(DesignMode::Light)\n .with_sync_env(|state, env| {\n env.locale = state.locale.clone();\n env.theme = AppDesignSystem::theme(state.theme_mode);\n })\n .run()?;\n\n\nThe common stateful builders now also expose the shared host key-handler and persistent reducer hooks where they were accidentally omitted. Mobile gains the matching live-test token builder. Terminal gains state initialization, startup action, design-system, frame-hook, and registry APIs. Its old closure-shaped with_env(|env| ...) convenience is renamed configure_env(...); with_env(...) now consistently takes a complete Env. Terminal font registration remains intentionally absent because the terminal emulator owns its font. Static and SSR retain build-time and request-time environment hooks because they do not have a persistent frame loop.\n\nThe routing reference now documents both synchronous and SQLite-backed asynchronous protected-route decisions at the router boundary. route_component publishes captured RouteParams during retained component conversion, so a matching component can read parameters without falling back to a function-built widget tree.\n\nFinally, the facade prelude is now rooted in the conflict-resolved public facade and includes the previously omitted built-in widget and terminal types. Public authoring widgets and the stateful shell APIs have substantive Rust documentation describing their behavior and parameters.