ci: consolidate into unified CI/CD pipeline workflow with parallel quality checks and gated deployment

[google-labs-jules]

Summary

This PR consolidates continuous integration and continuous deployment into a single, unified pipeline workflow defined in .github/workflows/deploy.yml and removes the redundant .github/workflows/ci.yml.

Changes Made

• Parallel Quality Verification Jobs: Split CI checks into three concurrent jobs (type-check, lint, and test) running static type-checking (bun run check), linting (bun run lint), and unit tests (bun run test).
• Gated Production Deployment: Configured the downstream deploy job with needs: [type-check, lint, test] to ensure production artifact compilation and GitHub Pages publishing only run after all upstream verification jobs succeed.
• Main Branch Restriction & PR Dry Runs: Added if: github.ref == 'refs/heads/main' to the deploy job to prevent pull requests from triggering deployment steps while ensuring quality checks run on both PRs and main branch pushes.
• Scoped Permissions: Restricted workflow permissions at the root to contents: read and attached deployment permissions (pages: write, id-token: write) exclusively to the downstream release job.

Acceptance Criteria Verified

• Pull requests run parallel type-checking, linting, and unit testing without triggering site deployment.
• Main branch updates halt deployment automatically if any validation check fails.
• Main branch updates automatically proceed to artifact compilation and site deployment when all checks pass.
• All verification and deployment operations are defined in a single consolidated pipeline file.