feat(run,notifications,profiles): stop sending prompts nobody typed, and fix notification + profile delivery

Run console:
- Picking a pipeline no longer pre-writes anything into the prompt box
  (`promptPrefill` in `LaneConsolePane.tsx` is gone — it wrote the driving
  slash command on a claude lane and a stage checklist on a codex one).
  Whatever sits in that box is sent as a real prompt the moment the run
  starts, so the box is the user's alone now.
- Resuming a session sends NO prompt at all (`handleStart` in `RunSetup.tsx`):
  the resumed session carries its own transcript, and leftover text in the box
  fired an extra turn into it.

Notifications:
- `client/src/lib/notify.ts` is now the ONE sender, used by both
  `useNotifications` and Settings' test button, and it reports where the
  notification landed: `POST /api/push/send` answering `{native:false,pushed:0}`
  means it went NOWHERE, so the client falls back to a local notification
  instead of counting the 200 as delivered.
- A notification carries the lane that raised it (`/workspace?lane=<id>`), and
  Workspace selects that lane on arrival.

Profiles:
- `server/lib/cc-profiles.js` reads and writes the macOS login Keychain item
  `Claude Code-credentials`, where the `claude` CLI actually keeps
  `claudeAiOauth` on darwin — a switch used to rewrite a file nothing reads.
  The file stays the fallback, is kept in step only when it already exists, and
  `AGENTHUB_CC_KEYCHAIN=0` pins it (tests set it).

Tests: npm run test:server (1820 pass), client vitest (553 pass).

client/src/lib/notify.ts

@@ -0,0 +1,85 @@
+/**
+ * @file Shows a browser notification — the single `notify()` both
+ * `useNotifications` (live events) and Settings' "Send Test Notification"
+ * button call, so the test proves the real delivery path and can report
+ * where it actually landed instead of a bare fire-and-forget.
+ * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
+ */
+
+export type NotifyVia = "native" | "push" | "local" | "blocked" | "none";
+
+export interface NotifyError {
+  statusCode?: number;
+  message?: string;
+}
+
+export interface NotifyResult {
+  via: NotifyVia;
+  errors: NotifyError[];
+}
+
+/**
+ * Prefers a server-relayed push (so it can arrive even if this tab isn't the
+ * active one, or the browser is backgrounded) and falls back to a local
+ * service-worker/`Notification` call when the server didn't deliver.
+ * @param title Notification title.
+ * @param body Notification body text.
+ * @param url Same-origin path to focus/navigate to on click (e.g. the lane
+ *   that raised this notification). Omit for notifications with no target.
+ */
+export async function notify(title: string, body: string, url?: string): Promise<NotifyResult> {
+  if (!("Notification" in window) || Notification.permission !== "granted") {
+    return { via: "blocked", errors: [] };
+  }
+
+  const errors: NotifyError[] = [];
+
+  // A 200 from /api/push/send means the request was ACCEPTED, not that anything
+  // reached the user: with no push subscription (no service worker, a
+  // non-secure origin, a browser that never subscribed) or a push service the
+  // server cannot reach, it answers `{ok:true, native:false, pushed:0}` and
+  // nobody is notified. Only `native` or `pushed > 0` is actual delivery —
+  // anything else falls through to the local notification below, which is why
+  // the fallback is keyed on the RESULT rather than on fetch throwing.
+  try {
+    const res = await fetch("/api/push/send", {
+      method: "POST",
+      headers: { "Content-Type": "application/json" },
+      body: JSON.stringify({ title, body, url }),
+    });
+    const result = res.ok ? await res.json().catch(() => null) : null;
+    if (result?.native) return { via: "native", errors };
+    if (result && result.pushed > 0) return { via: "push", errors };
+    if (!res.ok) errors.push({ statusCode: res.status });
+  } catch (e) {
+    errors.push({ message: e instanceof Error ? e.message : String(e) });
+  }
+
+  try {
+    // Vector, not `/favicon.ico` (32x32 raster) — crisp at whatever size the
+    // OS renders it, matching the icon server/lib/push.js already sends.
+    const data = url ? { url } : undefined;
+    if ("serviceWorker" in navigator) {
+      const registration = await navigator.serviceWorker.ready;
+      await registration.showNotification(title, {
+        body,
+        icon: "/favicon.svg",
+        silent: false,
+        data,
+      });
+    } else {
+      const n = new Notification(title, { body, icon: "/favicon.svg", data });
+      if (url) {
+        // No service worker to catch the click here — navigate this tab directly.
+        n.onclick = () => {
+          window.focus();
+          window.location.assign(url);
+        };
+      }
+    }
+    return { via: "local", errors };
+  } catch (e) {
+    errors.push({ message: e instanceof Error ? e.message : String(e) });
+    return { via: "none", errors };
+  }
+}