feat(maestro): end adapter children on daemon shutdown (#134)

SIGTERM now counts as a shutdown alongside ctrl-c: systemd stops the
unit with SIGTERM, and with KillMode=process nothing else would reach
the claude-code-acp children. After the listener drains the manager
terminates every adapter before the process exits.

crates/maestro-daemon/src/cli.rs

@@ -106,7 +106,7 @@ async fn run(config_override: Option<PathBuf>) -> Result<(), Box<dyn Error>> {
     projects.start_background_refresh();
 
     let router = local_api::router(local_api::state_for(
-        manager,
+        manager.clone(),
         config.hostname.clone(),
         config.home_dir.clone(),
         config.spawn_presets.clone(),
@@ -118,14 +118,25 @@ async fn run(config_override: Option<PathBuf>) -> Result<(), Box<dyn Error>> {
     let bound = listener.local_addr()?;
     tracing::info!(addr = %bound, "API listening");
 
+    // Ctrl-C at a terminal or SIGTERM from systemd: either one is a
+    // shutdown, and both must reach the adapter children below (#134). The
+    // unit's `KillMode=process` signals only the daemon, so nothing else
+    // would end them.
     let shutdown = async {
-        let _ = tokio::signal::ctrl_c().await;
-        tracing::info!("ctrl-c received — shutting down");
+        let mut sigterm = tokio::signal::unix::signal(tokio::signal::unix::SignalKind::terminate())
+            .expect("install SIGTERM handler");
+        tokio::select! {
+            _ = tokio::signal::ctrl_c() => tracing::info!("ctrl-c received — shutting down"),
+            _ = sigterm.recv() => tracing::info!("SIGTERM received — shutting down"),
+        }
     };
 
     axum::serve(listener, router)
         .tcp_nodelay(true)
         .with_graceful_shutdown(shutdown)
         .await?;
+    // tmux sessions outlive the daemon by design; structured sessions'
+    // adapter children do not (#134).
+    manager.shutdown().await;
     Ok(())
 }