Fix shadowing of Lua’s built-in type() function by renaming parameter in create_job

[cnra]

This PR fixes a runtime error caused by shadowing Lua's built-in type() function.
In encoder.lua, the function create_job used type as a parameter name, which overrides Lua's native type() function within its scope.

Specifically, at line 712, the code:

if type(on_finish_fn) == 'function' then
    on_finish_fn()
end

throws an error:

attempt to call upvalue 'type' (a string value)

because type was redefined as a string parameter instead of being the built-in function.

This fix renames the type parameter to job_type to avoid this naming conflict, resolving the error and preserving the intended behavior.