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/middleware.py

@@ -0,0 +1,27 @@
+from django.shortcuts import redirect
+
+
+class PortalStaffMiddleware:
+    """Keep customer accounts out of the staff portal. Webhooks stay public."""
+
+    PORTAL_PREFIX = "/portal/"
+    WEBHOOK_INFIX = "/webhooks/"
+
+    def __init__(self, get_response):
+        self.get_response = get_response
+
+    def __call__(self, request):
+        path = request.path
+        if path.startswith(self.PORTAL_PREFIX) and self.WEBHOOK_INFIX not in path:
+            user = getattr(request, "user", None)
+            if (
+                user is not None
+                and getattr(user, "is_authenticated", False)
+                and not getattr(user, "is_staff", False)
+            ):
+                from django.apps import apps
+
+                if apps.is_installed("shop"):
+                    return redirect("account:home")
+                return redirect("public:home")
+        return self.get_response(request)