Fix answer assignment indentation in search_sync (12sp -> 8sp)

Fix stream_search: backend_uuid and for loop must be inside try block

Fix indentation: thread_update blocks must be inside try

Fix thread_update UnboundLocalError in search functions

Fix list content handling in all message extractors

Fix return StreamingResponse inside async generator

Fix stream_search except indentation

Resolve merge conflict, keep our README

initial commit

v2: session-based multi-turn with backend_uuid follow-up, seamless fallback on session expiry