feat: Phase 6 - MCP + Webhooks + Worker + Polish

- MCP server: stateless JSON-RPC 2.0 with 18 tools (tasks, habits, projects, notes, domains, search, activity)
- Webhooks API: CRUD routes under /api/domains/[domainId]/webhooks/ with test endpoint and deliveries log
- Webhook delivery: HMAC-SHA256 signed POST with retry (exponential backoff, max 6)
- Worker rewrite: Drizzle ORM instead of PocketBase, polls jobs table, handles webhook_delivery, recurring_spawn, ai_dispatch
- Rate limiting: token bucket per IP/API key (100 req/min REST, 300 req/min MCP)
- Keyboard help overlay: ? opens Radix Dialog with search/filter, Esc closes
- AI @mention stub: @agent in command palette dispatches CustomEvent
- Mobile responsive: bottom nav, single-column kanban, day view calendar, 44px touch targets
- Accessibility: skip-to-content link, focus rings, aria-labels, color contrast
- E2E tests: mcp.spec.ts, webhooks.spec.ts, realtime.spec.ts added
- Schema: api_keys and webhook_deliveries tables with migration
- Removed old PocketBase-style database.ts from worker

apps/web/app/(dashboard)/layout.tsx

@@ -3,6 +3,7 @@ import { TopBar } from '@/components/topbar';
 import { NetworkErrorBanner } from '@/components/network-error-banner';
 import { KeyboardShortcutsProvider } from '@/components/keyboard-shortcuts-provider';
 import { WebVitalsTracker } from '@/components/web-vitals-tracker';
+import { MobileBottomNav } from '@/components/mobile-bottom-nav';
 
 export default function DashboardLayout({ children }: { children: React.ReactNode }) {
   return (
@@ -14,13 +15,14 @@ export default function DashboardLayout({ children }: { children: React.ReactNod
       <div className="flex min-h-screen">
         <NetworkErrorBanner />
         <Sidebar />
-        <div className="flex flex-1 flex-col">
+        <div className="flex flex-1 flex-col pb-16 md:pb-0">
           <TopBar />
           <main id="main-content" className="flex-1 overflow-auto p-6" tabIndex={-1}>
             {children}
           </main>
         </div>
       </div>
+      <MobileBottomNav />
       <div className="sr-only" aria-live="polite" aria-atomic="true" id="a11y-announcer" />
     </KeyboardShortcutsProvider>
   );