Replaced `DevExpress.Pdf.Core` with `DevExpress.Document.Processor` in `DocumentOperator.Infrastructure.csproj` to adopt a newer library for PDF processing. Removed the `Services\PdfProcessing\` folder reference.
Updated `DevExpressPdfProcessorTests` to reflect changes in the `ValidateAsync` method's behavior.
Introduced the `DevExpressPdfProcessor` class, implementing the `IPdfProcessor` interface. This class validates PDF documents and extracts metadata using the `DevExpress.Pdf` library. Added defensive input validation, metadata extraction, and exception handling for domain consistency.
Updated ROADMAP.md to reflect progress on the TDD process for
DevExpressPdfProcessor, including the creation of unit tests
(6 tests in the Red Phase). Updated progress to 4/7 mini-steps
completed and outlined the next step (Green Phase).
Added `DevExpressPdfProcessorTests.cs` with unit tests to
validate PDF files and extract metadata. Tests cover valid
PDFs, null/empty inputs, corrupted PDFs, and file size
calculations. Used `FluentAssertions` for assertions.
Cleaned up `DocumentOperator.Tests.csproj` by removing an
unused folder reference. No functional changes to the project
structure.
