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/managers/research_manager.py

@@ -3,7 +3,10 @@
 from __future__ import annotations
 
 from tradingagents.agents.schemas import ResearchPlan, render_research_plan
-from tradingagents.agents.utils.agent_utils import build_instrument_context
+from tradingagents.agents.utils.agent_utils import (
+    build_instrument_context,
+    get_language_instruction,
+)
 from tradingagents.agents.utils.structured import (
     bind_structured,
     invoke_structured_or_freetext,
@@ -37,7 +40,7 @@ Commit to a clear stance whenever the debate's strongest arguments warrant one;
 ---
 
 **Debate History:**
-{history}"""
+{history}""" + get_language_instruction()
 
         investment_plan = invoke_structured_or_freetext(
             structured_llm,