* Fix error string capitalization
Error strings often follow another string. Hence, they should not be
capitalized, unless referencing a name.
* Uncapitalize more error strings
While here, use %v on the error directly, which makes it easier to wrap
the error later with %w if need be.
* Uncapitalize more error strings
While here, rename Url to URL as a nitpick.
* Make mutating metadata ops mutation
* Implement scene generate screenshot
* Remove fetch policy on metadata mutations
* Port UI changes to v2.5
* Set generated image in database
SmallCoccinelle