Add shopper accounts, reviews, tracking, and seed_demo (#10)

## Summary
- Closes #9. Port shop-gated buyer accounts (register/login/profile, password reset, order history), purchase-gated reviews, and Stripe customer ids. Cards stay on Stripe.
- Slim public contact form to email + interest + message. Shipping tracking status, scan events, paste-in numbers, and EasyPost webhook when FEATURE_SHIPPING is on.
- Add template-neutral `seed_demo` (generic SKUs, demo shoppers, guest orders, tracking stubs). Prod refused. `--reset` deletes tagged demo rows after invoices.

## Test plan
- [ ] `cd site && uv run python manage.py test` (173 tests passed locally)
- [ ] Shop on: `/account/register`, login, profile, password reset, claim guest orders by email
- [ ] Shop off: `/account/` URLs absent; Sign in / Account links hidden
- [ ] Checkout as logged-in buyer stores `Order.user` and Stripe customer id; product review only after paid purchase
- [ ] Shipping on: portal paste-in tracking + EasyPost webhook updates status; shipping off: orders still work without tracking UI
- [ ] `seed_demo` refused in prod; `--reset` rebuilds tagged catalog/shoppers without deleting staff invoices

Reviewed-on: #10

site/public/notifications.py

@@ -26,8 +26,6 @@ def notify_admins_of_contact_form(lead: Lead) -> bool:
         return False
 
     contact = lead.contact
-    name = contact.full_name or "(no name)"
-    phone = contact.phone or "(none)"
     email = contact.email or "(none)"
     message = (lead.message or "").strip() or "(no message)"
 
@@ -35,27 +33,8 @@ def notify_admins_of_contact_form(lead: Lead) -> bool:
     portal_path = reverse("leads:detail", kwargs={"pk": lead.pk})
     portal_url = f"{site}{portal_path}" if site else portal_path
 
-    postal = contact.postal_address or {}
-    address_bits = [
-        postal.get("line1") or "",
-        postal.get("line2") or "",
-        ", ".join(
-            part
-            for part in [
-                postal.get("city") or "",
-                postal.get("state") or "",
-                postal.get("zip") or "",
-            ]
-            if part
-        ),
-    ]
-    address = "\n".join(bit for bit in address_bits if bit) or "(none)"
-
     ctx = email_brand_context(
-        name=name,
         email=email,
-        phone=phone,
-        address=address,
         message=message,
         portal_url=portal_url,
     )
@@ -63,7 +42,7 @@ def notify_admins_of_contact_form(lead: Lead) -> bool:
     html_content = get_template("emails/contact_email.html").render(ctx)
 
     mail = EmailMultiAlternatives(
-        subject=f"New contact form inquiry from {name}",
+        subject=f"New contact form inquiry from {email}",
         body=text_content,
         from_email=settings.DEFAULT_FROM_EMAIL,
         to=[to_email],