refactor(launcher): split CLI flow into command modules

Isolate process-side effects behind adapter seams and keep wrapper behavior stable while improving command-level testability.

launcher/process-adapter.ts

@@ -0,0 +1,21 @@
+export interface ProcessAdapter {
+  platform(): NodeJS.Platform;
+  onSignal(signal: NodeJS.Signals, handler: () => void): void;
+  writeStdout(text: string): void;
+  exit(code: number): never;
+  setExitCode(code: number): void;
+}
+
+export const nodeProcessAdapter: ProcessAdapter = {
+  platform: () => process.platform,
+  onSignal: (signal, handler) => {
+    process.on(signal, handler);
+  },
+  writeStdout: (text) => {
+    process.stdout.write(text);
+  },
+  exit: (code) => process.exit(code),
+  setExitCode: (code) => {
+    process.exitCode = code;
+  },
+};