Add a Settings > Email previews page showing every branded email with sample data

Renders the real templates every send function uses (claim approved,
membership invoice, invoice reminder) against hand-built placeholder
context -- no real Member/ClubMembership/DuesInvoice row needed, so
nothing here can leak real data. Each card shows the subject line and
toggles between the HTML render (in an iframe, so the email's own
markup can't clash with the page's) and the plain-text body, using
the same bg-steel pill-toggle pattern as the news preview's NL/EN
switch (generalised to .view-toggle-btn, kept .news-lang-btn as an
alias). Admin-only, alongside Club identity in Settings.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ECGMEwrc2k4D8VQuwjstj9

management/tests.py

@@ -26,6 +26,7 @@ from events.models import Attendance, Competition, Event, EventReferee, EventSer
 from events.services.rbihf_import import RBIHFImportError
 from events.services.recurrence import detach_occurrence, generate_occurrences
 from management.bulk_import import TEMPLATE_COLUMNS
+from management.email_previews import EMAIL_PREVIEWS
 from management.pdf import PDFExportError, _tint_with_white, referee_form_colors, render_pdf
 from management.recurrence_ui import build_rrule, describe_rrule, parse_rrule
 from members.models import Family, FamilyMembership, Group, GroupMembership, Member, ParentClaim
@@ -4765,6 +4766,61 @@ class ClubSettingsPreviewTests(ManagementTestBase):
         self.assertEqual(self.club.website, "https://ajax-united.example")
 
 
+class EmailPreviewListViewTests(ManagementTestBase):
+    """Settings > Email previews -- see management.email_previews."""
+
+    def setUp(self):
+        self.client.force_login(self.admin_user)
+
+    def test_renders_every_registered_preview(self):
+        response = self.club_get("email_preview_list")
+
+        self.assertEqual(response.status_code, 200)
+        for preview in EMAIL_PREVIEWS:
+            self.assertContains(response, preview.label)
+
+    def test_the_html_render_uses_the_clubs_own_branding(self):
+        self.club.name = "Ajax United"
+        self.club.secondary_color = "#123456"
+        self.club.save(update_fields=["name", "secondary_color"])
+
+        response = self.club_get("email_preview_list")
+
+        self.assertContains(response, "Ajax United")
+        self.assertContains(response, "#123456")
+
+    def test_the_subject_and_plain_text_body_render(self):
+        response = self.club_get("email_preview_list")
+
+        self.assertContains(response, "Subject:")
+        self.assertContains(response, "DUE-2026-00042")
+
+    def test_no_real_invoice_or_claim_data_is_needed(self):
+        # The whole point: a preview renders with zero DuesInvoice/ParentClaim
+        # rows in the database.
+        self.assertFalse(DuesInvoice.objects.exists())
+
+        response = self.club_get("email_preview_list")
+
+        self.assertEqual(response.status_code, 200)
+
+    def test_non_admin_gets_403(self):
+        coach_user = User.objects.create_user(email="coach-email-preview@example.com", password="pw-secret-123")
+        coach_member = Member.objects.create(user=coach_user, first_name="Cara", last_name="Coach")
+        team = Team.objects.create(club=self.club, name="U18", short_name="U18")
+        position = Position.objects.create(club=self.club, name="Coach14", short_name="C14", staff_position=True)
+        StaffAssignment.objects.create(team=team, member=coach_member, season=self.season, position=position)
+        self.client.force_login(coach_user)
+
+        response = self.club_get("email_preview_list")
+
+        self.assertEqual(response.status_code, 403)
+
+    def test_nav_entry_is_admin_only(self):
+        admin_response = self.club_get("club_settings")
+        self.assertContains(admin_response, reverse("management:email_preview_list"))
+
+
 class BillingEndingBannerTests(ManagementTestBase):
     """The club dashboard's "billing is about to stop" warning -- see
     management.views.HomeView and management/templates/management/home.html.