Fixture: events.subscription-result's sample secret is now a plain placeholder (the made-up whsec_ value matched GitHub's Stripe webhook-secret pattern; it was never a real secret: not in any production env file or database)

ddiff --git a/fixtures/events.subscription-result/valid/created.json b/fixtures/events.subscription-result/valid/created.json
iindex 5f8a2a28..17911087 100644
---- a/fixtures/events.subscription-result/valid/created.json
++++ b/fixtures/events.subscription-result/valid/created.json
@@@ -1 +1 @@
--{"id":"sub_01JAB2C3D4E5F6G7H8J9K0MNPQ","consumer":"live","topic_pattern":"media.vod.*","endpoint":"http://127.0.0.1:3000/internal/media-events","enabled":true,"retry_policy":null,"created_at":"2026-09-25T18:00:00.000Z","updated_at":"2026-09-25T18:00:00.000Z","secret":"whsec_4f1c0b8e2a9d7c6b5a4f3e2d1c0b9a8f7e6d5c4b3a2f1e0d9c8b7a6f5e4d3c2b"}
++{"id":"sub_01JAB2C3D4E5F6G7H8J9K0MNPQ","consumer":"live","topic_pattern":"media.vod.*","endpoint":"http://127.0.0.1:3000/internal/media-events","enabled":true,"retry_policy":null,"created_at":"2026-09-25T18:00:00.000Z","updated_at":"2026-09-25T18:00:00.000Z","secret":"example-signing-secret-not-real"}