Fix Docker container exit issue

Problem

The Docker container exits with code 0 instead of running as a persistent server, indicating the service is stopping unexpectedly after startup.

Expected Behavior

• Container should run continuously as a web server
• Service should be accessible on port 3000
• Container should restart automatically on failure

Proposed Solution

• Add proper runtime configuration to Dockerfile
• Implement healthchecks for container monitoring
• Ensure proper signal handling in the Rust application
• Add restart policies in docker-compose.yml

Acceptance Criteria

• Container runs persistently without exiting
• Healthcheck endpoint returns status
• Service is accessible on configured port
• Proper logging for troubleshooting
• Container restarts automatically on failure

Technical Details

• Review Dockerfile CMD/ENTRYPOINT configuration
• Add healthcheck endpoint to Rust application
• Configure proper signal handling for graceful shutdown
• Update docker-compose.yml with restart policies and healthchecks

Start by reviewing the Dockerfile CMD/ENTRYPOINT configuration and the service settings in docker-compose.yml, then inspect the Rust application startup and shutdown handling. Verify the container stays running, serves on port 3000, exposes a working healthcheck, logs troubleshooting information, and restarts automatically after failure.