feat: add movie creation endpoint

[marciomyst]

Summary

Implements the first movie catalog vertical slice for issue #11.

• Adds POST /api/movies with explicit request/response contracts.
• Adds a minimal Movie domain model, Application command handler, EF Core persistence, and migration.
• Adds validation for required fields, release year range, country code, genres, and duration.
• Updates API/domain/architecture docs and Spec Kit artifacts.

Impact

• API clients can create global movie catalog records without authentication for this slice.
• Successful creates return 201 Created, Location: /api/movies/{id}, and a stable movie response body.
• Invalid input returns ASP.NET Core ValidationProblemDetails.

Validation

• dotnet test backend/tests/SmartMovieCatalog.Domain.Tests/SmartMovieCatalog.Domain.Tests.csproj
• dotnet test backend/tests/SmartMovieCatalog.Application.Tests/SmartMovieCatalog.Application.Tests.csproj
• dotnet test backend/tests/SmartMovieCatalog.Api.Tests/SmartMovieCatalog.Api.Tests.csproj
• dotnet test backend/tests/SmartMovieCatalog.Infrastructure.Tests/SmartMovieCatalog.Infrastructure.Tests.csproj
• dotnet build SmartMovieCatalog.slnx

Notes

• GET /api/movies/{id} remains out of scope.
• Frontend movie creation UI remains out of scope.
• Existing unrelated local edits under specs/023-authentication-login-screen/* were not included.

Closes #11

[sonarqubecloud]

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
94.2% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud