browser relay: multi-session override, stale session recovery, better error feedback

- relay accepts new extension connections by closing old one (last wins, code 4000)
- extension recognizes code 4000 and stops auto-reconnect (shows "replaced" badge)
- fix ping interval race where old WS close handler killed new connection's pings
- retry CDP commands on "Session with given id not found" by re-attaching debugger
- describeError() maps known errors to user-friendly badge tooltips
- persisted relay tokens restored on server start
- user-scoped token salts, token regeneration/deletion endpoints
- extension download endpoint, integrations UI for browser relay setup
- browser relay env vars passed to pi-bridge sandboxes
- browser screen layout with chat panel and prompt prefix

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/apps/officer-web/Screens/Dashboard/Settings/IntegrationsSettings/index.tsx

@@ -1,5 +1,5 @@
 import { useMemo } from 'react';
-import { Puzzle, KeyRound, UserCircle, MessageCircle } from 'lucide-react';
+import { Puzzle, KeyRound, UserCircle, MessageCircle, Globe } from 'lucide-react';
 import type { LayoutNode, PanelComponents } from 'officerdev';
 import { WorkspaceLayout } from 'officerdev';
 import { useAuth } from 'hooks/useAuth';
@@ -15,6 +15,7 @@ import { TelegramBotConfig } from './TelegramBotConfig';
 import { TelegramAccount } from './TelegramAccount';
 import { WhatsAppBotConfig } from './WhatsAppBotConfig';
 import { WhatsAppAccount } from './WhatsAppAccount';
+import { BrowserRelay } from './BrowserRelay';
 
 const GLOBAL_KEY = 'INTEGRATIONS_SETTINGS_SELECTED';
 const TAB_KEY = 'INTEGRATIONS_SETTINGS_TAB';
@@ -79,6 +80,13 @@ const personalSections: SettingsSection[] = [
     description: 'Link your WhatsApp account',
     content: <WhatsAppAccount />,
   },
+  {
+    key: 'browser-relay',
+    icon: Globe,
+    title: 'Browser Relay',
+    description: 'Connect your Chrome browser',
+    content: <BrowserRelay />,
+  },
 ];
 
 const IntegrationsSidebar = () => {