Add cron container and per-household timezone for auto-reminders

- docker-compose.yml: meal-cron service loops send_reminders_cron.py every 60s
- send_reminders_cron.py: checks each household's local time, sends ntfy
  reminders at 10:00 (lunch) and 16:00 (dinner), guarded against duplicates
- models.py: timezone, last_lunch_reminder, last_dinner_reminder on households
- meals.py: /admin/timezone route for admins to set household timezone
- dashboard: timezone selector (20 common zones) in Account Settings
- i18n: 5 new translation keys for timezone strings
- Dockerfile: copy send_reminders_cron.py
- tests: 4 new timezone tests (admin set, non-admin denied, default UTC, auth)
- docs: updated AGENTS.md

send_reminders_cron.py

@@ -0,0 +1,81 @@
+#!/usr/bin/env python3
+"""Run by the cron container every ~60s to send meal reminders.
+
+For each household, checks the current local time.  If it's 10:00–10:04,
+sends lunch reminders; if 16:00–16:04, sends dinner reminders.  A
+per-household sent-date guard prevents duplicate sends.
+"""
+
+import os
+import sys
+from datetime import datetime
+from zoneinfo import ZoneInfo, available_timezones
+
+# Ensure we can import from the app directory
+sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
+
+from models import get_all_households, get_users_with_ntfy, update_reminder_sent, init_db
+from ntfy import send_meal_reminder
+
+APP_BASE_URL = os.environ.get("APP_BASE_URL", "http://meal-tracker:5000")
+
+# Reminder schedule (local time)
+REMINDERS = {
+    "lunch": 10,   # 10:00
+    "dinner": 16,  # 16:00
+}
+
+
+def _resolve_timezone(tz_str: str) -> ZoneInfo:
+    """Return a ZoneInfo for *tz_str*, falling back to UTC on error."""
+    try:
+        return ZoneInfo(tz_str)
+    except Exception:
+        return ZoneInfo("UTC")
+
+
+def main() -> None:
+    init_db()  # ensure tables exist (first run before web container)
+    now_utc = datetime.now(ZoneInfo("UTC"))
+    sent = 0
+
+    for hh in get_all_households():
+        tz = _resolve_timezone(hh.get("timezone", "UTC"))
+        local_now = now_utc.astimezone(tz)
+        today_str = local_now.strftime("%Y-%m-%d")
+        hour = local_now.hour
+        minute = local_now.minute
+
+        for meal_type, trigger_hour in REMINDERS.items():
+            if hour != trigger_hour or minute >= 5:
+                continue
+
+            last_col = f"last_{meal_type}_reminder"
+            if hh.get(last_col) == today_str:
+                continue  # already sent today
+
+            users = get_users_with_ntfy(hh["id"])
+            if not users:
+                continue
+
+            for user in users:
+                ok = send_meal_reminder(
+                    ntfy_url=user["ntfy_url"],
+                    ntfy_token=user["ntfy_token"],
+                    callback_token=user["callback_token"],
+                    meal_type=meal_type,
+                    for_date=local_now.date(),
+                    app_base_url=APP_BASE_URL,
+                )
+                if ok:
+                    print(f"[{local_now:%Y-%m-%d %H:%M}] sent {meal_type} → {user['username']}")
+                    sent += 1
+
+            update_reminder_sent(hh["id"], meal_type, today_str)
+
+    if sent:
+        print(f"Sent {sent} reminder(s)")
+
+
+if __name__ == "__main__":
+    main()