Updated PHASENPLAN.md and ROADMAP.md to reflect a complete restructuring of the development plan and added a "Bugfix: Attachment Detection" entry.
Implemented attachment detection in DevExpressPdfProcessor.cs using the new `DetectEmbeddedFiles` method, which scans raw PDF data for the `/EmbeddedFiles` keyword. Updated the `hasAttachments` property to use this method and set `attachmentCount` to `-1` when attachments are detected.
Added a new test, `ValidateAsync_PdfWithoutAttachments_ReturnsNoAttachments`, in DevExpressPdfProcessorTests.cs to verify that PDFs without attachments are correctly identified. Included a note about future testing for PDFs with attachments using ZUGFeRD files.
All related tests are passing (12/12 green).
Eliminated a redundant `using DevExpress.Pdf;` statement to improve code readability and maintain cleaner imports. This change has no functional impact but enhances code clarity.
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.
