refactor: fix camel case to be true camelCase and add pascal case

[omegagussan]

This PR refactors the naming conventions:

• Camel case (camel): Now produces true camelCase with lowercase first letter (e.g., thisIsAProperty)
• Pascal case (pascal): New option that produces PascalCase with uppercase first letter (e.g., ThisIsAProperty) - this was the old camel behavior
• Updated all documentation and error messages to include the new pascal option
• Updated test files to use pascal naming scheme for struct names (since Go structs need to be exported)

The changes ensure that:

• JSON property keys can use true camelCase via --convert-keys camel
• Struct names can use PascalCase via --naming-scheme pascal (required for exported Go types)
• Backward compatibility: users who want the old camel behavior should use pascal instead

[omegagussan]

@lerenn I dont seem to understand how these CI examples work. Do you think it can be something in the github actions layer thats broken generically that Ive not caused?

[lerenn]

@omegagussan Yeah sorry about that, I have a PR on it's way to fix these. It's not related to your changes :)

[omegagussan]

@lerenn It seems I cant retrigger the github actions for CI if this is fixed. Can you?