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/i18n/locales/en/settings.json

@@ -84,7 +84,11 @@
     "sessionComplete": "Session completes",
     "sessionError": "Session errors",
     "subagentSpawned": "Subagent spawned",
+    "testBlocked": "The browser has not granted notification permission.",
     "testBody": "Notifications are working!",
+    "testFailed": "Nothing could be shown.",
+    "testLocal": "Your browser has no push subscription, so this was shown locally. Web Push needs a secure origin (localhost or HTTPS) and a registered service worker.",
+    "testSent": "Sent via push — check your notification centre.",
     "testTitle": "Agent Monitor",
     "title": "Notifications",
     "turnComplete": "Claude finishes a turn"