Add PostgreSQL support and EF Core migrations for local development. Introduces ApplicationDbContext, adds Npgsql.EntityFrameworkCore.PostgreSQL and EF Core Design packages, and includes generated migrations (InitialPostgres and RemoveTestItems) plus updated model snapshot. Program.cs now loads an optional API/appsettings.custom.json, configures the DbContext from ConnectionStrings:Postgres and runs Database.Migrate() on startup. Adds a Dev docker-compose.yml to run postgres + pgAdmin, pins dotnet-ef in dotnet-tools.json, and adds ConnectionStrings to appsettings files. Also ignores API/appsettings.custom.json in .gitignore and updates README/codexInfo to document the new DB/dev workflow.
Add Swashbuckle.AspNetCore (v6.6.2) to API project and register Swagger services (AddEndpointsApiExplorer, AddSwaggerGen). Enable UseSwagger/UseSwaggerUI only in Development to expose /swagger for API exploration without affecting production behavior. Update codexInfo.md to document the dev-only Swagger endpoint.
Switch backend to serve the built SPA and static assets, add a minimal health endpoint, and clean up template code. Changes: added API/Controllers/HealthController.cs (GET /api/health -> 200), removed WeatherForecast controller and model, removed OpenAPI package reference and OpenAPI wiring from API.csproj/Program.cs, updated Program.cs to serve wwwroot with default files/static files and a SPA fallback that returns index.html for non-/api routes (/api/* returns 404), updated GUI/vite.config.ts to output build to API/wwwroot and clear the directory, added API/wwwroot to .gitignore, and updated codexInfo.md to document these changes. This enables the GUI build to be deployed directly into the API project and served as a single-page app.
Jonas