Add `P'revious support to page_splitter.

gemini_for_labels.py

@@ -306,7 +306,7 @@ def process_copy_group(group_key, files):
 
 # Run ThreadPool on GROUPS (Copies), not individual files
 # Each thread handles one student's full exam copy sequentially
-with ThreadPoolExecutor(max_workers=6) as executor:
+with ThreadPoolExecutor(max_workers=8) as executor:
     # Convert dict items to arguments for map
     # executor.map expects a function and an iterable.
     # We use a lambda or separate function to unpack the tuple if needed,