[BUG] scala-cask generates invalid enum entries

Description

When generating enums there are several problems.

1. Unlike all the other code this appears to try to use the braceless syntax, but fails as the case statements are not correctly indented. I suspect it would be much simpler to use braces rather that trying to force the indentation levels in the mustache templates

2. A Scala 3 enum should be of the form:-

   enum derives RW {
      case a,b,c,d
      }

rather than having multiple cases. Also the cases in my case(s) ended up as integers, scala requires identifiers

3. Although the use of derives RW seems to work elsewhere, when used with enums it gets an is imported twice on the same import line.

openapi-generator version

7.10

Start by reproducing the Scala 3 enum output from the scala-cask generator using the reported OpenAPI Generator 7.10 setup. Inspect the mustache templates and generated imports for enum indentation, case identifiers, enum syntax, and duplicate derives RW imports. Done means the generated Scala compiles and produces valid enums with correct imports.