Phase 1: Repository cleanup, Docker Compose setup, and environment config

Summary:

• Flatten backend/ and frontend/ directory structure
• Remove broken imports and stale test files
• Fix hardcoded API URL to use VITE_API_URL env var
• Add CORS middleware to backend
• Add docker-compose.yml with PostgreSQL, backend, and frontend services
• Add Dockerfiles for backend and frontend
• Add database/init.sql with service and incident tables
• Add .env.example, .dockerignore files, and root README.md
• Update .gitignore and commit package-lock.json files

Differential Revision: https://devcentral.nasqueron.org/D3962