// Package launcher manages the application lifecycle for Go services.
//
// It orchestrates a sequence of phases — init, assemble, start, wait, shutdown —
// across a set of registered [Component] implementations. Any infrastructure piece
// (database pool, HTTP server, background worker) that implements the three-method
// Component interface can be managed by the launcher.
//
// # Lifecycle
//
//	OnInit  (all components, in order)   ← open connections, allocate resources
//	BeforeStart hooks (in order)         ← wire dependencies after all inits done
//	OnStart (all components, in order)   ← start goroutines, begin serving
//	--- application is running ---
//	OnStop  (all components, reverse)    ← graceful shutdown, release resources
//
// # Basic wiring
//
//	logger := logz.New(logz.Options{})
//	lc := launcher.New(logger)
//
//	lc.Append(db, cache, server)
//	lc.BeforeStart(func() error {
//	    return server.RegisterRoutes(db, cache)
//	})
//
//	if err := lc.Run(); err != nil {
//	    logger.Error("launcher failed", err)
//	    os.Exit(1)
//	}
//
// Run blocks until SIGINT/SIGTERM is received or [Launcher.Shutdown] is called,
// then stops all components in reverse order before returning.
package launcher