feat: initialize monorepo with full dev team best practices

- Unified monorepo with backend (Express), frontend (Next.js), and devops
- Backend: ESLint, Prettier, Jest tests (3 passing), health endpoint, .env.example
- Frontend: Fixed build errors, fixed all lint errors (0 remaining), tests passing
- DevOps: Docker Compose with PostgreSQL, backend, frontend + healthchecks
- CI/CD: 3 GitHub Actions workflows (backend, frontend, docker integration)
- DX: Husky pre-commit hooks with smart change detection
- Docs: Root README with architecture, CONTRIBUTING.md, PR template

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.gitignore

@@ -0,0 +1,44 @@
+# Dependencies
+node_modules/
+.pnp.*
+
+# Build outputs
+dist/
+.next/
+out/
+build/
+*.tsbuildinfo
+
+# Environment files
+.env
+.env.local
+.env.*.local
+
+# IDE
+.idea/
+.vscode/
+*.swp
+*.swo
+
+# OS
+.DS_Store
+Thumbs.db
+
+# Logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+pnpm-debug.log*
+
+# Testing
+coverage/
+.nyc_output/
+
+# Docker
+*.pid
+*.seed
+
+# Misc
+.cache/
+.parcel-cache/
+.eslintcache