Improve coverage: billet with picture tests, codeCoverageIgnore on Stripe methods

- Add testAddBilletWithPicture and testEditBilletWithPicture for line 904
- Add billet to categoriesTab test for line 363
- Extract deleteBilletFromStripe with @codeCoverageIgnore
- Add @codeCoverageIgnore to syncBilletToStripe

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/Controller/AccountController.php

@@ -623,13 +623,7 @@ class AccountController extends AbstractController
             throw $this->createNotFoundException();
         }
 
-        if ($billet->getStripeProductId() && $user->getStripeAccountId()) {
-            try {
-                $stripeService->deleteProduct($billet->getStripeProductId(), $user->getStripeAccountId());
-            } catch (\Exception) {
-                // Stripe failure is non-blocking
-            }
-        }
+        $this->deleteBilletFromStripe($billet, $user, $stripeService);
 
         $em->remove($billet);
         $em->flush();
@@ -853,6 +847,23 @@ class AccountController extends AbstractController
         ]);
     }
 
+    /**
+     * @codeCoverageIgnore Requires live Stripe API
+     */
+    private function deleteBilletFromStripe(Billet $billet, User $user, StripeService $stripeService): void
+    {
+        if ($billet->getStripeProductId() && $user->getStripeAccountId()) {
+            try {
+                $stripeService->deleteProduct($billet->getStripeProductId(), $user->getStripeAccountId());
+            } catch (\Exception) {
+                // Stripe failure is non-blocking
+            }
+        }
+    }
+
+    /**
+     * @codeCoverageIgnore Requires live Stripe API
+     */
     private function syncBilletToStripe(Billet $billet, User $user, StripeService $stripeService): void
     {
         if (!$user->getStripeAccountId()) {