feat(pdfengines): add embed feature

pkg/gotenberg/mocks.go

@@ -53,6 +53,7 @@ type PdfEngineMock struct {
 	ReadMetadataMock  func(ctx context.Context, logger *zap.Logger, inputPath string) (map[string]interface{}, error)
 	WriteMetadataMock func(ctx context.Context, logger *zap.Logger, metadata map[string]interface{}, inputPath string) error
 	EncryptMock       func(ctx context.Context, logger *zap.Logger, inputPath, userPassword, ownerPassword string) error
+	EmbedFilesMock    func(ctx context.Context, logger *zap.Logger, filePaths []string, inputPath string) error
 }
 
 func (engine *PdfEngineMock) Merge(ctx context.Context, logger *zap.Logger, inputPaths []string, outputPath string) error {
@@ -83,6 +84,10 @@ func (engine *PdfEngineMock) Encrypt(ctx context.Context, logger *zap.Logger, in
 	return engine.EncryptMock(ctx, logger, inputPath, userPassword, ownerPassword)
 }
 
+func (engine *PdfEngineMock) EmbedFiles(ctx context.Context, logger *zap.Logger, filePaths []string, inputPath string) error {
+	return engine.EmbedFilesMock(ctx, logger, filePaths, inputPath)
+}
+
 // PdfEngineProviderMock is a mock for the [PdfEngineProvider] interface.
 type PdfEngineProviderMock struct {
 	PdfEngineMock func() (PdfEngine, error)

pkg/gotenberg/pdfengine.go

@@ -143,6 +143,10 @@ type PdfEngine interface {
 	// The ownerPassword provides full access to the document.
 	// If the ownerPassword is empty, it defaults to the userPassword.
 	Encrypt(ctx context.Context, logger *zap.Logger, inputPath, userPassword, ownerPassword string) error
+
+	// EmbedFiles embeds files into a PDF. All files are embedded as file attachments
+	// without modifying the main PDF content.
+	EmbedFiles(ctx context.Context, logger *zap.Logger, filePaths []string, inputPath string) error
 }
 
 // PdfEngineProvider offers an interface to instantiate a [PdfEngine].