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>

Cargo.lock

@@ -1242,6 +1242,7 @@ dependencies = [
  "brahman-handshake",
  "brahman-sidecar",
  "gpui",
+ "yahweh-launcher",
  "yahweh-theme",
  "yahweh-widget-app-header",
  "yahweh-widget-banner",
@@ -6215,6 +6216,7 @@ version = "0.1.0"
 dependencies = [
  "gpui",
  "minga-store",
+ "yahweh-launcher",
  "yahweh-theme",
  "yahweh-widget-app-header",
  "yahweh-widget-banner",
@@ -6484,6 +6486,7 @@ dependencies = [
  "serde_json",
  "tempfile",
  "uuid",
+ "yahweh-launcher",
  "yahweh-meta-runtime",
  "yahweh-theme",
  "yahweh-widget-app-header",
@@ -6882,6 +6885,7 @@ dependencies = [
  "brahman-sidecar",
  "gpui",
  "nouser-card",
+ "yahweh-launcher",
  "yahweh-theme",
  "yahweh-widget-app-header",
  "yahweh-widget-banner",
@@ -12944,6 +12948,14 @@ dependencies = [
  "yahweh-theme",
 ]
 
+[[package]]
+name = "yahweh-launcher"
+version = "0.1.0"
+dependencies = [
+ "gpui",
+ "yahweh-theme",
+]
+
 [[package]]
 name = "yahweh-meta-runtime"
 version = "0.1.0"