Customer accounts, order tracking, and purchase reviews (#8)

## Summary
- Slim the public contact form to email, interest, and message. Name, phone, and address live on the customer profile instead.
- Customers can register, sign in, save shipping details, and view order history. Logged-in checkout creates a Stripe Customer and saves cards on Stripe (`setup_future_usage`); we only store `stripe_customer_id`.
- Shipment tracking: EasyPost tracker lookup + webhook, plus paste-in numbers from Pirate Ship/Shippo. Customers see carrier status on their orders; `dispatch_due` refreshes open shipments.
- Product reviews (1–5) only after a paid/fulfilled purchase of that product.

Fixes #7

## Test plan
- [ ] Contact form submits with only email + message; extra name/phone/address fields are ignored
- [ ] Register, sign in, save profile (name/phone/shipping)
- [ ] Guest checkout still works; after signup, prior orders with that email show in history
- [ ] Logged-in checkout prefills shipping and does not collect card data locally
- [ ] Portal: buy label or paste a Pirate Ship tracking number, confirm status/events; customer order page shows tracking
- [ ] Product page: non-buyers cannot review; buyers can leave one 1–5 star review
- [ ] Non-staff users hitting `/portal/` redirect to `/account/`

Reviewed-on: #8

site/accounts/services.py

@@ -0,0 +1,22 @@
+from accounts.models import CustomerProfile
+
+
+def get_customer_profile(user) -> CustomerProfile:
+    profile, _created = CustomerProfile.objects.get_or_create(user=user)
+    return profile
+
+
+def claim_orders_for_user(user) -> int:
+    """Attach guest orders that used this email so history/reviews work after signup."""
+    from django.apps import apps
+
+    if not apps.is_installed("shop"):
+        return 0
+    from shop.models import Order
+
+    email = (user.email or user.username or "").strip()
+    if not email:
+        return 0
+    return Order.objects.filter(user__isnull=True, email__iexact=email).update(
+        user=user
+    )