Reconcile: your admin wins, keeping main's non-admin work

You built a self-service catalogue admin on feature/admin-and-ui-wins while I built a
competing one that had already merged and deployed. Both forked from 27821cd. Per your
call, your implementation is the one that stays.

Kept from main (files your branch didn't touch, so no conflict):
- the CI test gate (tests now run and block the image)
- motion 12.42.2
- the platform contract test

Took from your branch:
- split AdminProductController / AdminCategoryController + ProductPhotoService (server-side
  webp via cwebp)
- a real category table (Category, V3__categories.sql) behind the product filters
- pages/Admin.tsx, with server-side /admin protection that redirects a browser to Authentik
  and returns it to /admin afterward — cleaner than my client-side gate, and it avoids the
  post-login-to-home issue my version had

Deleted my competing admin (AdminController, MeController, pages/admin/*, auth.tsx, and my
admin tests).

Grafted onto your gallery: swipe + arrow keys, which the deployed version had and yours
didn't. Added an AdminSecurityTest for your endpoints (admin closed, shop public, contact
CSRF) — the admin was otherwise untested, and CI now gates on tests.

Verified against a running container: /admin redirects a browser to Authentik (a bare 401
only for */* fetches, which is correct). 25 tests green.

frontend/src/pages/Contact.tsx

@@ -1,5 +1,5 @@
 import { useState } from 'react';
-import { submitContact } from '@/lib/api';
+import { csrfHeader } from '@/lib/api';
 
 type Status = 'idle' | 'sending' | 'sent' | 'error';
 
@@ -24,7 +24,16 @@ const ContactPage = () => {
     setStatus('sending');
     setError('');
     try {
-      await submitContact(formData);
+      // csrfHeader() is empty unless security is switched on, so this posts the same as it always
+      // has on a deployment with no identity provider — and keeps working once one is configured,
+      // where an unaccompanied POST would otherwise be rejected.
+      const res = await fetch('/api/contact', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json', ...csrfHeader() },
+        body: JSON.stringify(formData),
+      });
+      const data = await res.json();
+      if (!res.ok) throw new Error(data.error || 'Could not send the message.');
       setStatus('sent');
       setFormData({ name: '', email: '', message: '' });
     } catch (err) {