Built-in case transformation implementation.

This transform handles the standard case transformations:

• :upper - All uppercase
• :lower - All lowercase
• :capitalize - First letter uppercase
• :invert - First letter lowercase, rest uppercase
• :random - Randomly upper or lower (adds entropy)
• :none - No transformation

Examples

transform = %ExkPasswd.Transform.CaseTransform{mode: :upper}
ExkPasswd.Transform.apply(transform, "hello", config)
#=> "HELLO"

transform = %ExkPasswd.Transform.CaseTransform{mode: :random}
ExkPasswd.Transform.apply(transform, "hello", config)
#=> "HELLO" or "hello" (random)