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>

scheduler/daemon.py

@@ -515,6 +515,69 @@ def _check_per_user_midnight_schedules():
             )
 
 
+def check_task_reminders():
+    """Check one-off tasks for advance and at-time reminders."""
+    from datetime import timedelta
+    try:
+        tasks = postgres.select("tasks", where={"status": "pending"})
+        if not tasks:
+            return
+
+        user_tasks = {}
+        for task in tasks:
+            uid = task.get("user_uuid")
+            user_tasks.setdefault(uid, []).append(task)
+
+        for user_uuid, task_list in user_tasks.items():
+            now = _user_now_for(user_uuid)
+            current_hhmm = now.strftime("%H:%M")
+            current_date = now.date()
+            user_settings = None  # lazy-load once per user
+
+            for task in task_list:
+                raw_dt = task.get("scheduled_datetime")
+                if not raw_dt:
+                    continue
+                sched_dt = (
+                    raw_dt
+                    if isinstance(raw_dt, datetime)
+                    else datetime.fromisoformat(str(raw_dt))
+                )
+                sched_date = sched_dt.date()
+                sched_hhmm = sched_dt.strftime("%H:%M")
+                reminder_min = task.get("reminder_minutes_before") or 0
+
+                # Advance reminder
+                if reminder_min > 0 and not task.get("advance_notified"):
+                    adv_dt = sched_dt - timedelta(minutes=reminder_min)
+                    if adv_dt.date() == current_date and adv_dt.strftime("%H:%M") == current_hhmm:
+                        if user_settings is None:
+                            user_settings = notifications.getNotificationSettings(user_uuid)
+                        if user_settings:
+                            msg = f"⏰ In {reminder_min} min: {task['title']}"
+                            if task.get("description"):
+                                msg += f" — {task['description']}"
+                            notifications._sendToEnabledChannels(user_settings, msg, user_uuid=user_uuid)
+                        postgres.update("tasks", {"advance_notified": True}, {"id": task["id"]})
+
+                # At-time reminder
+                if sched_date == current_date and sched_hhmm == current_hhmm:
+                    if user_settings is None:
+                        user_settings = notifications.getNotificationSettings(user_uuid)
+                    if user_settings:
+                        msg = f"📋 Now: {task['title']}"
+                        if task.get("description"):
+                            msg += f"\n{task['description']}"
+                        notifications._sendToEnabledChannels(user_settings, msg, user_uuid=user_uuid)
+                    postgres.update(
+                        "tasks",
+                        {"status": "notified", "updated_at": datetime.utcnow().isoformat()},
+                        {"id": task["id"]},
+                    )
+    except Exception as e:
+        logger.error(f"Error checking task reminders: {e}")
+
+
 def poll_callback():
     """Called every POLL_INTERVAL seconds."""
     # Create daily schedules per-user at their local midnight
@@ -537,6 +600,7 @@ def poll_callback():
     # Original checks
     check_routine_reminders()
     check_refills()
+    check_task_reminders()
 
 
 def daemon_loop():