feat(agent): support Responses steering and project-aware tools

Use the dedicated TJWATER_AGENT_URL and Responses stream protocol. Keep running
turns active while users steer or queue follow-ups and edit pending delivery.
Refresh the model catalog before generation and preserve approval mode selection.

Integrate scoped investigation messaging/presentation, geographic place selection,
current Agent composer styles and supporting workbench contracts.

Validation: 77 focused Vitest checks, 21 browser cases, lint, typecheck and
production build. Preserve direct Server/Agent routing and project authentication.

src/features/workbench/hooks/workbench-event-channel.ts

@@ -0,0 +1,25 @@
+import type { WorkbenchEvent } from "../api/workbench-sync-client";
+
+export type WorkbenchStreamNotification =
+  | { type: "open" | "disconnect" | "reset" }
+  | { type: "events"; events: WorkbenchEvent[] };
+
+/** Presentation observes wire events before business acknowledgements or snapshot filtering. */
+export class WorkbenchEventChannel {
+  private listeners = new Set<(notification: WorkbenchStreamNotification) => void>();
+  private live = false;
+
+  subscribe = (listener: (notification: WorkbenchStreamNotification) => void) => {
+    this.listeners.add(listener);
+    listener({ type: this.live ? "open" : "disconnect" });
+    return () => { this.listeners.delete(listener); };
+  };
+
+  publish(notification: WorkbenchStreamNotification) {
+    if (notification.type !== "events") this.live = notification.type === "open";
+    for (const listener of this.listeners) {
+      // One presentation observer must not interrupt authoritative business synchronization.
+      try { listener(notification); } catch { /* Observers own their error presentation. */ }
+    }
+  }
+}