Migrate Jenkins to GitHub Actions: consolidated CI/CD pipeline

[devin-ai-integration]

Summary

Replaces 4 separate GitHub Actions workflow files (lint.yml, deploy.yml, playwright.yml, security-tests.yml) with a single consolidated CI/CD pipeline (ci.yml), structured like a Jenkinsfile with sequential stages and proper dependencies:

lint → unit-tests → build → e2e-tests ──┐
                          → security-tests ──┤→ deploy (main only)

Key changes:

• New unit test stage — Runs bun run test (Vitest), which was previously missing from CI
• Proper stage ordering — Each stage depends on the previous, failing fast on lint/test errors before heavier E2E runs
• Parallel test execution — E2E and security tests run in parallel after the build stage
• Conditional deploy — Release creation only runs on push to main after all tests pass
• Build artifact upload — Build output uploaded as an artifact for traceability

All existing functionality (format check, Playwright E2E, security tests, GitHub Release creation, old release cleanup) is preserved.

Review & Testing Checklist for Human

• Verify the ci.yml pipeline triggers correctly on PRs to main — check that all stages (lint, unit-tests, build, e2e-tests, security-tests) run and pass
• Confirm the deploy stage does not run on pull requests (it should only trigger on push to main)
• After merging, verify a push to main triggers the full pipeline including the deploy/release stage

Notes

• No Jenkinsfile was found in the repository — the migration consolidates the existing separate workflows into a single pipeline with the structure and stage dependencies typical of a Jenkins pipeline
• The unit-tests stage is new — it runs Vitest (bun run test -- --run) which was not previously part of any CI workflow

Link to Devin session: https://app.devin.ai/sessions/adc75c1385354b7a80ea21261362a886
Requested by: @vanessasalas-cog

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[devin-ai-integration]

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