Match banner brand, print splash, optional crop, and demo seed (#6)

## Summary
- Rebrand public site, portal, and emails from Ecoprint orange to the PRINTFORGE banner palette (navy / cyan / lime).
- Replace the loading splash with a CSS 3D-print animation; product uploads get a default-on smart crop + background filter checkbox.
- Add `manage.py seed_demo` for client walkthroughs on dev/beta only (refuses prod).

Closes #5.

## Test plan
- [ ] Public pages and buttons are cyan/lime, not orange
- [ ] Splash shows a printer building a model (or a static print if reduced motion)
- [ ] Product edit: smart-crop checked by default; uncheck stores the original photo
- [ ] `uv run python manage.py seed_demo` fills shop, contacts, leads, orders, campaigns
- [ ] `DJANGO_ENV=prod` seed_demo exits with an error

Reviewed-on: #6

site/shop/views.py

@@ -298,10 +298,12 @@ def portal_product_edit(request, pk=None):
                     remove_product_images(
                         product, request.POST.getlist("remove_image")
                     )
+                    smart_crop = request.POST.get("smart_crop", "on") == "on"
                     append_product_images(
                         product,
                         uploads=request.FILES.getlist("images"),
                         user=request.user,
+                        smart_crop=smart_crop,
                     )
                     for key, color in colors.items():
                         uploads = request.FILES.getlist(f"color_images_{key}")
@@ -312,6 +314,7 @@ def portal_product_edit(request, pk=None):
                             uploads=uploads,
                             user=request.user,
                             color=color,
+                            smart_crop=smart_crop,
                         )
                     refresh_listing_image(product)
                     _delete_replaced_file(