Update messages and minor fixes

[klaidliadon]

• Detect the go version in go.mod and use it in make proto and make generate (go 1.25 introduces some compile errors)
• Fix Admin JWT scope checking for multiple scopes: instead of strings.Contains, we split the scopes using , and check if the service is in the list
• Added some tests to check that the session is upgraded only on a scope match
• Updated error message for rate limit error