Gate inbox delivery on worker-side steer ACK

Replace the fire-and-forget steer with a correlated ACK round-trip so main
only marks an inbox row delivered once the worker confirms the message
landed on the live Agent. Steer against a run that is still in the
`preparing` window or has already started `closing` now falls back to the
wake + inbox projection path instead of being silently dropped.

Worker publishes `run-agent-state` transitions at Agent construction and
teardown; main tracks these on `ActiveRunContext.state` and refuses to
steer runs that are not `agent_active`. A rejected or timed-out ACK
triggers `wakeAgentIfPossible` so the next `prepareRun` replays the row.

src/main/service-graph/create-worker-service.ts

@@ -7,6 +7,7 @@ import type { createBudgetEnforcementService } from "../budget-enforcement-servi
 import type { createSessionManagementService } from "../session-management-service";
 import type { PiRuntimeServices } from "../service-graph-pi-runtime";
 import type { NotificationOptions } from "../notification-service";
+import type { RuntimeMessageInjector } from "../agent-runtime";
 import type { LateBinding } from "./late-binding";
 
 export interface WorkerServiceDeps {
@@ -29,6 +30,12 @@ export interface WorkerServiceDeps {
   budgetService: ReturnType<typeof createBudgetEnforcementService>;
   sessionService: ReturnType<typeof createSessionManagementService>;
   piRuntimeRef: { current: PiRuntimeServices | null };
+  /**
+   * Resolver for the late-constructed runtime message injector. The worker
+   * message handler needs it to route `steer-ack` child messages, but the
+   * injector is assembled after the worker service itself.
+   */
+  getRuntimeMessageInjector: () => RuntimeMessageInjector | null;
 }
 
 /**
@@ -52,6 +59,7 @@ export function buildWorkerService(deps: WorkerServiceDeps) {
     budgetService,
     sessionService,
     piRuntimeRef,
+    getRuntimeMessageInjector,
   } = deps;
 
   const wakeAgentIfPossible = (agentId: string | null | undefined, companyId: string, trigger: string) =>
@@ -83,5 +91,6 @@ export function buildWorkerService(deps: WorkerServiceDeps) {
     budgetService,
     sessionService,
     getRuntimeBridge: () => piRuntimeRef.current?.runtimeBridge ?? null,
+    getRuntimeMessageInjector,
   });
 }

src/main/service-graph/late-binding.ts

@@ -26,6 +26,10 @@ export class LateBinding<T> {
     return this.value;
   }
 
+  isAssigned(): boolean {
+    return this.assigned;
+  }
+
   clear(): void {
     this.value = null;
     this.assigned = false;