feat: tasks app, security hardening, mobile fixes, iOS app shell

- Custom SQLite task manager replacing TickTick wrapper
- 73 tasks migrated from TickTick across 15 projects
- RRULE recurrence engine with lazy materialization
- Dashboard tasks widget (desktop sidebar + mobile card)
- Tasks page with project tabs, add/edit/complete/delete
- Security: locked ports to localhost, removed old containers
- Gitea Actions runner configured and all 3 CI jobs passing
- Fixed mobile overflow on dashboard cards
- iOS Capacitor app shell (Second Brain)
- Frontend/backend guide docs for adding new services
- TickTick Google Calendar sync re-authorized

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend-v2/src/lib/components/layout/Navbar.svelte

@@ -39,6 +39,10 @@
 		<div class="navbar-links">
 			<a href="/" class="navbar-link" class:active={page.url.pathname === '/'}>Dashboard</a>
 
+			{#if showApp('tasks')}
+				<a href="/tasks" class="navbar-link" class:active={isActive('/tasks')}>Tasks</a>
+			{/if}
+
 			{#if showApp('trips')}
 				<a href="/trips" class="navbar-link" class:active={isActive('/trips')}>Trips</a>
 			{/if}