feat(yahweh-launcher): F3 — extracción del shell standard de explorers

Iter 19. Patrón con 4 consumers idénticos: cada main() repetía el mismo
~20 líneas de boot (Application::new + Theme::install_default +
cx.open_window + WindowOptions + cx.activate). Sólo varían título,
tamaño y root factory.

crates/modules/ui_engine/libs/launcher/:
- pub fn launch_app(title, size, root_factory) → 1-line boot.
- pub fn launch_app_with(config, root_factory) → variante con config
  armado afuera (env-var driven, etc).
- pub struct AppLaunchConfig::new(title, size).
- 2 tests cubren normalización del config.

Migración 4 consumers (nakui/nouser/minga/brahman-broker explorer):
- main() pasa de ~20 líneas a 1: launch_app(...).
- Imports gpui podados (no más App/Application/Bounds/WindowOpts/etc).
- Cada uno agrega dep yahweh-launcher.

Naming: yahweh-shell ya existe (bootstrap heavyweight con file/db/text
viewers en crates/apps/). Helper liviano queda como yahweh-launcher.

Ahorro ~75 líneas de boot hardcoded. Cambios de window/theme boot
ahora en un solo lugar.

2/2 tests launcher; 4 consumer suites intactas, todo verde.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/apps/nakui-explorer/src/main.rs

@@ -26,39 +26,20 @@ use std::path::PathBuf;
 use std::time::Duration;
 
 use gpui::{
-    div, prelude::*, px, rgb, App, Application, Bounds, Context, IntoElement, Render,
-    SharedString, Window, WindowBounds, WindowOptions,
+    div, prelude::*, px, rgb, Context, IntoElement, Render, SharedString, Window,
 };
 use nakui_core::event_log::{EventLog, LogEntry};
+use yahweh_launcher::launch_app;
 use yahweh_meta_runtime::{preview_value, short_hash, short_uuid};
 use yahweh_theme::Theme;
-use yahweh_widget_banner::{banner_themed, Banner};
 use yahweh_widget_app_header::app_header;
+use yahweh_widget_banner::{banner_themed, Banner};
 use yahweh_widget_card::card_themed;
 
 const REFRESH_INTERVAL: Duration = Duration::from_secs(2);
 
 fn main() {
-    Application::new().run(|cx: &mut App| {
-        // Theme global instalado al boot — los widgets themed lo
-        // requieren, y simplifica el chrome del app a una paleta
-        // consistente.
-        Theme::install_default(cx);
-        let bounds = Bounds::centered(None, gpui::size(px(900.), px(640.)), cx);
-        cx.open_window(
-            WindowOptions {
-                window_bounds: Some(WindowBounds::Windowed(bounds)),
-                titlebar: Some(gpui::TitlebarOptions {
-                    title: Some(SharedString::from("Nakui — Event Log")),
-                    ..Default::default()
-                }),
-                ..Default::default()
-            },
-            |_w, cx| cx.new(Explorer::new),
-        )
-        .expect("open window");
-        cx.activate(true);
-    });
+    launch_app("Nakui — Event Log", (900., 640.), Explorer::new);
 }
 
 /// Estado de la vista. `entries` se reescribe en cada tick (el log