Admin for the menu and enquiries, plus gallery fixes

Admin
- /api/admin: products CRUD, the enquiry inbox, and presigned photo upload straight to the
  bucket so images never pass through the app. Gated by platform.security.authenticated-paths
  = /api/admin/**, so any signed-in Authentik user is staff — the alternative is a role model
  a two-person bakery would never maintain.
- /api/me is deliberately PUBLIC. The SPA asks on every page load, and requiring a login
  would bounce every anonymous visitor to Authentik just to read the menu.
- /admin screens: product list with edit and remove, an editor with drag-free photo
  reordering and upload, and an enquiry inbox that flags anything the relay refused.

Gallery
- swipe on touch devices, which the react-awesome-slider it replaced had and this did not,
  plus arrow keys and position dots — with swipe there is otherwise nothing to say a card
  holds more than one photo. Vertical drags are ignored so page scrolling still works.
- @BatchSize on the photo collection: the products page loaded the whole catalogue and
  Hibernate issued a query per product for its images, forty-odd round trips for a page
  that needs two.

Three things the tests caught, none of which are obvious:
- Adding the storage starter broke every existing test. It activates on a default endpoint,
  so an S3 client is built even in tests and dies on blank keys.
- MockMvc's webAppContextSetup leaves the security filter chain OUT, so the first version of
  the security test passed 200s and proved the opposite of what it claimed. It needs
  .apply(springSecurity()).
- Turning on the security starter turns on CSRF — for the PUBLIC contact form too, which
  then 403s. The SPA now reads the XSRF-TOKEN cookie and sends X-XSRF-TOKEN, and there is a
  test asserting the form is rejected without it.

pom.xml

@@ -62,8 +62,16 @@
             <groupId>net.thebennett.platform</groupId>
             <artifactId>platform-starter-contact</artifactId>
         </dependency>
-        <!-- No starter-security: this is a public brochure site with nothing to sign in to, and no
-             starter-storage: the photos are served straight from the public MinIO bucket. -->
+        <!-- Admin needs a login, and uploading a product photo needs the bucket. The public site
+             still reads photos straight from the bucket's public URLs. -->
+        <dependency>
+            <groupId>net.thebennett.platform</groupId>
+            <artifactId>platform-starter-security</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>net.thebennett.platform</groupId>
+            <artifactId>platform-starter-storage</artifactId>
+        </dependency>
 
         <!-- test -->
         <!-- Contract tests every app on the platform inherits. -->
@@ -77,6 +85,13 @@
             <artifactId>spring-boot-starter-test</artifactId>
             <scope>test</scope>
         </dependency>
+        <!-- springSecurity() for MockMvc: without it the filter chain is absent and every protected
+             path answers 200, which would make a security test prove the opposite of what it says. -->
+        <dependency>
+            <groupId>org.springframework.security</groupId>
+            <artifactId>spring-security-test</artifactId>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-testcontainers</artifactId>