Initialize backend project structure #1

Goal

Initialize the Python backend structure that will support the VisualGraph application.

The initial setup should provide a clean foundation for the API, graph integration, computer vision modules, and automated tests.

Tasks

• Create the backend/ directory
• Configure Python dependency management
• Create the visual_graph package
• Create the application entry point
• Create the initial test structure
• Configure basic development dependencies
• Verify that the application can be imported and executed locally

Acceptance Criteria

• The backend can be installed locally
• The visual_graph package can be imported successfully
• A basic application entry point exists
• The test directory is recognized by the test runner
• Dependencies are reproducible from the project configuration