With Nextcloud 32 we ship a new default background: "Fluid" by Jo Myoung Hee.
Copyright by Nextcloud GmbH under the CC-BY-SA-4.0
- added the background compressed as WebP (90% quality)
- set as new default
- added license reference and move theming related reuse config
Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>
