Modularize and streamline billing templates; replace _billing_form.html with reusable modals and shared partials, and update styles and interactions for consistency and clarity. billing, feature management, and forms

Refactored club detail templates to modularize common UI components. Standardized layout, interactions, and styles across admin, billing, and feature cards for consistency and reusability.

controlpanel/tests.py

@@ -1297,7 +1297,9 @@ class BillingFormRenderTests(ControlPanelTestBase):
         self.tier = Tier.objects.create(name="Standard")
         TierPrice.objects.create(tier=self.tier, active_from=self.today - datetime.timedelta(days=1200), amount=Decimal("500.00"))
 
-    def test_the_billing_forms_render(self):
+    def test_the_billing_forms_are_post_only(self):
+        # Every one of these is reachable only through a modal on the billing or club
+        # detail page: there is no standalone template to render on a GET.
         subscribe(self.club, self.tier)
         due = self.club.dues.first()
 
@@ -1309,17 +1311,33 @@ class BillingFormRenderTests(ControlPanelTestBase):
             reverse("controlpanel:club_open_period", args=[self.club.pk]),
             reverse("controlpanel:due_pay", args=[due.pk]),
         ):
-            self.assertEqual(self.client.get(url).status_code, 200, url)
+            self.assertEqual(self.client.get(url).status_code, 405, url)
 
-    def test_the_payment_form_defaults_to_the_outstanding_balance(self):
+    def test_the_billing_forms_redirect_with_a_message_on_invalid_input(self):
+        # Rejected input has nowhere to re-render — the modal that submitted it is on a
+        # page this view no longer serves — so it must bounce back with an error message
+        # rather than 500 or silently drop the submission.
+        subscribe(self.club, self.tier)
+        due = self.club.dues.first()
+
+        response = self.client.post(reverse("controlpanel:tier_create"), {"name": "", "description": "", "is_active": "on"}, follow=True)
+        self.assertRedirects(response, reverse("controlpanel:billing"))
+        self.assertContains(response, "This field is required")
+
+        response = self.client.post(reverse("controlpanel:due_pay", args=[due.pk]), {"amount": "not-a-number", "method": "bank_transfer", "reference": "", "paid_at": "", "note": ""}, follow=True)
+        self.assertRedirects(response, reverse("controlpanel:club_detail", args=[self.club.pk]))
+        self.assertContains(response, "Enter a number")
+
+    def test_the_payment_modal_defaults_to_the_outstanding_balance(self):
         subscribe(self.club, self.tier)
         due = self.club.dues.first()
         record_payment(due, Decimal("200.00"))
         due.refresh_from_db()
 
-        response = self.client.get(reverse("controlpanel:due_pay", args=[due.pk]))
+        response = self.client.get(reverse("controlpanel:club_detail", args=[self.club.pk]))
 
-        self.assertEqual(response.context["form"].initial["amount"], Decimal("300.00"))
+        rendered_due = next(rendered for rendered in response.context["dues"] if rendered.pk == due.pk)
+        self.assertEqual(rendered_due.payment_form.initial["amount"], Decimal("300.00"))
 
     def test_a_tier_can_be_renamed(self):
         self.client.post(reverse("controlpanel:tier_update", args=[self.tier.pk]), {"name": "Standard plus", "description": "", "is_active": "on"})