Add active-turn steering (#3394)

* feat(agents): add active-turn steering

Let users choose whether an immediate prompt interrupts or joins the active turn. The daemon owns exact-turn admission, provider delivery, safe fallback, and canonical timeline identity while queueing remains client-side.

* fix(agents): stabilize steering history and replay QA

* fix(agents): preserve steering timeline order

* fix(agents): reconcile resumed provider history

* fix(agents): serialize steering with cancellation

* test(agents): prove Claude multi-tool steering

* test(agents): force explicit history hydration

* fix(agents): flush output before steer admission

packages/app/src/composer/input/state.ts

@@ -1,8 +1,9 @@
 import type { DaemonClient } from "@getpaseo/client/internal/daemon-client";
+import type { ActiveTurnBehavior } from "@getpaseo/protocol/messages";
 import type { MessagePayload } from "@/composer/types";
 import type { MessageInputKeyboardActionKind } from "@/keyboard/actions";
 
-export type SendBehavior = "interrupt" | "queue";
+export type SendBehavior = ActiveTurnBehavior | "queue";
 
 interface ComposerSurfaceState {
   opacity: 0 | 1;