fix: search_handler yields bytes and handle None in entity_extended_d…

[TheRealKingS]

fix: search_handler yields bytes and handle None in entity_extended_display

• search_handler yielded str from dumps() instead of bytes, causing TypeError in gunicorn when streaming search results
• entity_extended_display could return None for display/info causing AttributeError on .strip() when searching for SPs

Tested on pyFF 2.1.5 with gunicorn 25.1.0 and Python 3.12

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