The simple_oauth gem had deprecation warnings with Ruby 3.4's URI module.
Since we only use basic OAuth 1.0a HMAC-SHA1 signing, implemented a minimal
OAuth module directly in the gem. This removes an external dependency and
fixes the deprecation warnings.
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>
