🐛 sbb_textline_detection: Set pcGtsId

Newest OCR-D workspace validation requires that the pcGtsId of a
PAGE-XML file matches its METS mets:file/ID. Fix this by setting
it correctly.

qurator/sbb_textline_detector/ocrd_cli.py

@@ -77,6 +77,7 @@ class OcrdSbbTextlineDetectorRecognize(Processor):
 
             # Create a new PAGE file from the input file
             pcgts = page_from_file(self.workspace.download_file(input_file))
+            pcgts.set_pcGtsId(file_id)
             page = pcgts.get_Page()
 
             # Merge results → PAGE file