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/shop/admin.py

@@ -1,6 +1,13 @@
 from django.contrib import admin
 
-from shop.models import Order, OrderItem, Product, ProductColor, ProductImage
+from shop.models import (
+    Order,
+    OrderItem,
+    Product,
+    ProductColor,
+    ProductImage,
+    ProductReview,
+)
 
 
 class ProductColorInline(admin.TabularInline):
@@ -22,6 +29,13 @@ class ProductAdmin(admin.ModelAdmin):
     inlines = [ProductColorInline, ProductImageInline]
 
 
+@admin.register(ProductReview)
+class ProductReviewAdmin(admin.ModelAdmin):
+    list_display = ("product", "user", "rating", "created_at")
+    list_filter = ("rating",)
+    search_fields = ("product__name", "user__email", "title")
+
+
 class OrderItemInline(admin.TabularInline):
     model = OrderItem
     extra = 0
@@ -34,4 +48,5 @@ class OrderAdmin(admin.ModelAdmin):
     list_display = ("number", "email", "amount", "status", "created_at")
     list_filter = ("status",)
     search_fields = ("number", "email", "customer_name")
+    raw_id_fields = ("user",)
     inlines = [OrderItemInline]