fix(theming): previews need the same file extension as their originals

Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>

apps/theming/REUSE.toml

@@ -22,13 +22,13 @@ SPDX-FileCopyrightText = "2022 Nextcloud GmbH and Nextcloud contributors"
 SPDX-License-Identifier = "AGPL-3.0-or-later"
 
 [[annotations]]
-path = ["img/background/jo-myoung-hee-fluid.webp", "img/background/jo-myoung-hee-fluid-dark.webp", "img/background/preview/jo-myoung-hee-fluid.jpg"]
+path = ["img/background/jo-myoung-hee-fluid.webp", "img/background/jo-myoung-hee-fluid-dark.webp", "img/background/preview/jo-myoung-hee-fluid.webp"]
 precedence = "aggregate"
 SPDX-FileCopyrightText = "2025 Nextcloud GmbH"
 SPDX-License-Identifier = "CC-BY-SA-4.0"
 
 [[annotations]]
-path = ["img/background/jenna-kim-the-globe.webp", "img/background/jenna-kim-the-globe-dark.webp", "img/background/preview/jenna-kim-the-globe.jpg"]
+path = ["img/background/jenna-kim-the-globe.webp", "img/background/jenna-kim-the-globe-dark.webp", "img/background/preview/jenna-kim-the-globe.webp"]
 precedence = "aggregate"
 SPDX-FileCopyrightText = "2024 Nextcloud GmbH"
 SPDX-License-Identifier = "CC-BY-SA-4.0"

cypress/e2e/theming/themingUtils.ts

@@ -5,7 +5,7 @@
 import { colord } from 'colord'
 
 export const defaultPrimary = '#00679e'
-export const defaultBackground = 'jenna-kim-the-globe.webp'
+export const defaultBackground = 'jo-myoung-hee-fluid.webp'
 
 /**
  * Check if a CSS variable is set to a specific color