Add one-off tasks/appointments feature

- DB: tasks table with scheduled_datetime, reminder_minutes_before, advance_notified, status
- API: CRUD routes GET/POST /api/tasks, PATCH/DELETE /api/tasks/<id>
- Scheduler: check_task_reminders() fires advance + at-time notifications, tracks advance_notified to prevent double-fire
- Bot: handle_task() with add/list/done/cancel/delete actions + datetime resolution helper
- AI: task interaction type + examples added to command_parser
- Web: task list page with overdue/notified color coding + new task form with datetime-local picker
- Nav: replaced Templates with Tasks in bottom nav

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

synculous-client/src/app/dashboard/layout.tsx

@@ -14,8 +14,7 @@ import {
   PillIcon,
   SettingsIcon,
   LogOutIcon,
-  CopyIcon,
-
+  ClockIcon,
   SunIcon,
   MoonIcon,
 } from '@/components/ui/Icons';
@@ -24,7 +23,7 @@ import Link from 'next/link';
 const navItems = [
   { href: '/dashboard', label: 'Today', icon: HomeIcon },
   { href: '/dashboard/routines', label: 'Routines', icon: ListIcon },
-  { href: '/dashboard/templates', label: 'Templates', icon: CopyIcon },
+  { href: '/dashboard/tasks', label: 'Tasks', icon: ClockIcon },
   { href: '/dashboard/history', label: 'History', icon: CalendarIcon },
   { href: '/dashboard/stats', label: 'Stats', icon: BarChartIcon },
   { href: '/dashboard/medications', label: 'Meds', icon: PillIcon },