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/public/sw.js

@@ -87,13 +87,19 @@ self.addEventListener("push", (event) => {
 
 self.addEventListener("notificationclick", (event) => {
   event.notification.close();
+  const url = event.notification.data?.url;
   event.waitUntil(
     clients.matchAll({ type: "window" }).then((windowClients) => {
       for (const client of windowClients) {
-        if (client.focus) {
+        if ("focus" in client) {
+          // Reuse an already-open tab instead of stacking a new one — that's
+          // also why `navigate` (same-origin only) beats postMessage: it works
+          // even if the page hasn't wired up a listener for this.
+          if (url && "navigate" in client) client.navigate(url).catch(() => {});
           return client.focus();
         }
       }
+      if (url && clients.openWindow) return clients.openWindow(url);
     })
   );
 });