Add CI/CD Pipeline

[Technical-1]

Priority: Medium
Labels: ci/cd, automation

Description:
Add GitHub Actions workflow (.github/workflows/ci.yml) to run tests on push/PR, build for multiple platforms, and add release workflow for tags.

Files to create:

• .github/workflows/ci.yml
• .github/workflows/release.yml (optional)

Acceptance criteria:

• CI workflow runs tests on push/PR
• Builds for Linux, macOS, Windows
• Release workflow creates releases on tags
• Workflow runs in reasonable time
• Status badges added to README

Implementation notes:

• Create .github/workflows/ directory
• Use actions-rs/cargo for Rust builds
• Test on ubuntu-latest, macos-latest, windows-latest
• Add release workflow for creating GitHub releases
• Add status badges to README