fix: translate Chinese prompts to English in simulation config and profile generators

- simulation_config_generator.py: translate all LLM prompts and system messages
- oasis_profile_generator.py: translate profile generation prompts

Ensures get_language_instruction() controls output language instead of
being overridden by Chinese prompt context.

backend/app/services/oasis_profile_generator.py

@@ -671,7 +671,7 @@ class OasisProfileGenerator:
     
     def _get_system_prompt(self, is_individual: bool) -> str:
         """获取系统提示词"""
-        base_prompt = "你是社交媒体用户画像生成专家。生成详细、真实的人设用于舆论模拟,最大程度还原已有现实情况。必须返回有效的JSON格式，所有字符串值不能包含未转义的换行符。"
+        base_prompt = "You are a social media user persona generation expert. Generate detailed, realistic personas for opinion simulation, maximizing fidelity to real-world situations. Must return valid JSON format, all string values must not contain unescaped newlines."
         return f"{base_prompt}\n\n{get_language_instruction()}"
     
     def _build_individual_persona_prompt(
@@ -687,7 +687,7 @@ class OasisProfileGenerator:
         attrs_str = json.dumps(entity_attributes, ensure_ascii=False) if entity_attributes else "无"
         context_str = context[:3000] if context else "无额外上下文"
         
-        return f"""为实体生成详细的社交媒体用户人设,最大程度还原已有现实情况。
+        return f"""Generate detailed social media user persona for the entity, maximizing fidelity to real-world situations.
 
 实体名称: {entity_name}
 实体类型: {entity_type}
@@ -736,7 +736,7 @@ class OasisProfileGenerator:
         attrs_str = json.dumps(entity_attributes, ensure_ascii=False) if entity_attributes else "无"
         context_str = context[:3000] if context else "无额外上下文"
         
-        return f"""为机构/群体实体生成详细的社交媒体账号设定,最大程度还原已有现实情况。
+        return f"""Generate detailed social media account settings for organization/group entity, maximizing fidelity to real-world situations.
 
 实体名称: {entity_name}
 实体类型: {entity_type}
@@ -769,7 +769,7 @@ class OasisProfileGenerator:
 - persona必须是一段连贯的文字描述，不要使用换行符
 - {get_language_instruction()} (gender字段必须用英文"other")
 - age必须是整数30，gender必须是字符串"other"
-- 机构账号发言要符合其身份定位"""
+- Organization account posts must match its identity positioning"""
     
     def _generate_profile_rule_based(
         self,
@@ -1076,11 +1076,11 @@ class OasisProfileGenerator:
         - name: 用户真实姓名
         - username: 系统中的用户名
         - user_char: 详细人设描述（注入到LLM系统提示中，指导Agent行为）
-        - description: 简短的公开简介（显示在用户资料页面）
+        - description: Short public bio (displayed on user profile page)
         
-        user_char vs description 区别：
+        user_char vs description difference:
         - user_char: 内部使用，LLM系统提示，决定Agent如何思考和行动
-        - description: 外部显示，其他用户可见的简介
+        - description: Externally displayed, visible to other users
         """
         import csv
         
@@ -1112,7 +1112,7 @@ class OasisProfileGenerator:
                     profile.name,           # name: 真实姓名
                     profile.user_name,      # username: 用户名
                     user_char,              # user_char: 完整人设（内部LLM使用）
-                    description             # description: 简短简介（外部显示）
+                    description             # description: Short bio (externally displayed)
                 ]
                 writer.writerow(row)