feat: cli launcher npx kandev (#39)

* feat: cli launcher

* feat: improved debug

apps/cli/src/process.ts

@@ -0,0 +1,34 @@
+import kill from "tree-kill";
+
+export type ChildLike = { pid?: number | undefined };
+
+export function createProcessSupervisor(): {
+  children: ChildLike[];
+  shutdown: (reason: string) => Promise<void>;
+  attachSignalHandlers: () => void;
+} {
+  let shuttingDown = false;
+  const children: ChildLike[] = [];
+
+  const shutdown = async (reason: string) => {
+    if (shuttingDown) return;
+    shuttingDown = true;
+    console.log(`[kandev] shutting down (${reason})...`);
+    await Promise.all(
+      children
+        .filter((child) => child.pid)
+        .map((child) => new Promise<void>((resolve) => kill(child.pid as number, "SIGTERM", () => resolve()))),
+    );
+  };
+
+  const onSignal = (signal: NodeJS.Signals) => {
+    void shutdown(`signal ${signal}`).then(() => process.exit(0));
+  };
+
+  const attachSignalHandlers = () => {
+    process.on("SIGINT", onSignal);
+    process.on("SIGTERM", onSignal);
+  };
+
+  return { children, shutdown, attachSignalHandlers };
+}