📝 Update EF migration instructions for .NET Aspire integration

[danielmackay]

This pull request updates the README.md to provide clearer instructions for running the solution and managing Entity Framework (EF) migrations, especially in the context of .NET Aspire orchestration. The documentation now includes step-by-step guides for running the solution, adding, applying, and removing EF migrations, and highlights Aspire-specific considerations.

Improvements to developer documentation:

• Added a new "Running the Solution" section with OS-specific instructions for starting the app and accessing Swagger UI.
• Introduced a comprehensive "EF Migrations" section, detailing how to add, apply, and remove migrations using both native .NET tooling and the Aspire CLI, and explained Aspire-specific migration behaviors and caveats.

[Copilot]

Pull Request Overview

This PR updates the README documentation to reflect the integration of .NET Aspire orchestration. The changes reorganize sections to better guide developers through running the solution and working with EF migrations in an Aspire-orchestrated environment.

• Moves the "Running the Solution" section earlier in the documentation
• Adds comprehensive EF migration instructions specific to .NET Aspire
• Documents the use of Aspire CLI commands for migration management