ci: Start a CI pipeline

[bryanalves]

Note

Low Risk
Low risk since this only introduces CI configuration and does not change application/runtime code; failures would be limited to build/test execution in CI.

Overview
Introduces a new CircleCI config (.circleci/config.yml) that runs builds in a ruby:3.1.4 container, installs Bundler 2.4.10, installs gems, and executes bundle exec rake (default test task) to gate changes via CI.

^{Reviewed by Cursor Bugbot for commit fb791e3. Bugbot is set up for automated code reviews on this repo. Configure here.}

[ForwardFinancingAdmin]

✅ Snyk checks have passed. No issues have been found so far.

Status	Scan Engine	Critical	High	Medium	Low	Total (0)
✅	Code Security	0	0	0	0	0 issues

💻 Catch issues earlier using the plugins for VS Code, JetBrains IDEs, Visual Studio, and Eclipse.