feat: add daemon skeleton with lifecycle management

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/daemon/lifecycle.ts

@@ -0,0 +1,34 @@
+type ShutdownHandler = () => Promise<void>;
+
+export class Lifecycle {
+  private shutdownHandlers: ShutdownHandler[] = [];
+  private shuttingDown = false;
+  private _isRunning = true;
+
+  get isRunning(): boolean {
+    return this._isRunning;
+  }
+
+  onShutdown(handler: ShutdownHandler): void {
+    this.shutdownHandlers.push(handler);
+  }
+
+  async shutdown(): Promise<void> {
+    if (this.shuttingDown) return;
+    this.shuttingDown = true;
+    this._isRunning = false;
+
+    console.log('Shutting down...');
+
+    // Execute handlers in reverse order (LIFO)
+    for (const handler of [...this.shutdownHandlers].reverse()) {
+      try {
+        await handler();
+      } catch (error) {
+        console.error('Shutdown handler error:', error);
+      }
+    }
+
+    console.log('Shutdown complete');
+  }
+}