feat(i18n): localize researchers, risk debators, research mgr, trader

output_language config now propagates to every user-facing agent.
Previously only the four analysts and portfolio manager respected
the setting, producing partial-localization reports with English
debate text interleaved with non-English analyst sections. Verified
live: 7 agents produce Chinese output when config is set to Chinese.

#575

tradingagents/agents/researchers/bear_researcher.py

@@ -1,3 +1,4 @@
+from tradingagents.agents.utils.agent_utils import get_language_instruction
 
 
 def create_bear_researcher(llm):
@@ -31,7 +32,7 @@ Company fundamentals report: {fundamentals_report}
 Conversation history of the debate: {history}
 Last bull argument: {current_response}
 Use this information to deliver a compelling bear argument, refute the bull's claims, and engage in a dynamic debate that demonstrates the risks and weaknesses of investing in the stock.
-"""
+""" + get_language_instruction()
 
         response = llm.invoke(prompt)