fix(tasks): add -- end-of-options separator to ocrmypdf command in convert_to_pdfa

The test_successful_conversion test asserts that '--' precedes the input/output
file paths in the ocrmypdf command as a security measure against argument
injection (file paths starting with '-' being interpreted as options).
The implementation was missing this separator, causing the test to fail and
triggering a downstream pytest INTERNALERROR (OSError: Bad file descriptor)
when pytest's terminal writer tried to report the failure.

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>
Agent-Logs-Url: https://github.com/christianlouis/DocuElevate/sessions/bd7ef195-4b30-456e-8118-5c200fb4bf45

app/tasks/convert_to_pdfa.py

@@ -78,6 +78,7 @@ def _convert_pdf_to_pdfa(input_path: str, output_path: str, pdfa_format: str = "
         output_type,
         "--quiet",
         "--invalidate-digital-signatures",
+        "--",  # end-of-options separator: prevents file paths from being interpreted as options
         input_path,
         output_path,
     ]