[Foundation] Implement CI/CD pipeline with GitHub Actions

[coderabbitai]

Overview

Set up automated CI/CD pipeline for builds, tests, and deployments.

Current State

• No .github/workflows directory
• Manual build process only
• No automated quality checks

Requirements

• Create GitHub Actions workflow for PR checks
• Add lint + format + typecheck jobs
• Add test execution and coverage reporting
• Set up EAS Build integration for iOS/Android
• Add web build workflow (Netlify)
• Implement automated release workflow
• Add security scanning (Dependabot, CodeQL)
• Configure branch protection rules

Success Criteria

• All PRs must pass CI before merge
• Automated builds on main branch
• Release workflow with semantic versioning

Priority: CRITICAL

Estimated Effort: 3-4 days

Labels: foundation, ci-cd, priority:critical

Backlink: Related to PR #2