chore: initial project setup with backend, frontend, and infrastructure

Add complete NexaPantry application structure including:
- Docker Compose configuration with PostgreSQL, Redis, FastAPI backend, worker, frontend and Caddy
- Environment configuration template with database, auth, and service settings
- GitHub Actions CI workflow for backend/frontend linting, testing, auditing and Docker builds
- AGPL-3.0 license and comprehensive README with setup, development, and security documentation
- Backend

backend/app/services/notifications.py

@@ -0,0 +1,50 @@
+import logging
+from datetime import UTC, date, datetime, timedelta
+
+from sqlalchemy import select
+from sqlalchemy.orm import Session
+
+from app.models.entities import Home, HomeMembership, Notification, Product
+from app.services.mail import send_mail
+
+logger = logging.getLogger(__name__)
+
+
+def create_expiry_notifications(db: Session) -> int:
+    count = 0
+    homes = db.scalars(select(Home)).all()
+    today = date.today()
+    for home in homes:
+        deadline = today + timedelta(days=home.expiry_warning_days)
+        products = db.scalars(
+            select(Product).where(Product.home_id == home.id, Product.expires_at <= deadline)
+        ).all()
+        if not products:
+            continue
+        memberships = db.scalars(select(HomeMembership).where(HomeMembership.home_id == home.id)).all()
+        for membership in memberships:
+            prefs = membership.notification_preferences or {}
+            if prefs.get("in_app", True):
+                db.add(
+                    Notification(
+                        user_id=membership.user_id,
+                        home_id=home.id,
+                        title="NexaPantry expiry warning",
+                        body=f"{len(products)} products expire soon in {home.name}.",
+                        kind="expiry",
+                    )
+                )
+                count += 1
+            if prefs.get("email", False):
+                try:
+                    send_mail(db, membership.user.email, "NexaPantry expiry warning", f"{len(products)} products expire soon in {home.name}.")
+                except Exception:
+                    logger.exception("Expiry e-mail delivery failed for user %s", membership.user_id)
+                    continue
+    db.commit()
+    return count
+
+
+def mark_read(db: Session, notification: Notification) -> Notification:
+    notification.read_at = datetime.now(UTC)
+    return notification