[frinsdev]

Summary

• Replace flat parameters: methods with resource namespaces aligned to Semaphore’s API (messages, priority, otp, account)
• Add RSpec + WebMock coverage, RuboCop, and GitHub Actions CI (Ruby 3.1–3.4)
• Bump gem version to 2.0.0 (breaking change)

New API

client.messages.send(...)
client.messages.bulk_send(...)
client.messages.retrieve(id)
client.messages.list(...)
client.priority.send(...)
client.otp.send(...)
client.account.retrieve