fix(i18n): replace remaining hardcoded language directives in LLM prompts

- oasis_profile_generator: replace hardcoded "使用中文" with dynamic get_language_instruction()
- ontology_generator: remove hardcoded "（中文）" from schema annotation
- report_agent: replace Chinese-specific language consistency rules with language-neutral ones
- zep_tools: dynamically select quote style based on locale

backend/app/services/ontology_generator.py

@@ -67,7 +67,7 @@ ONTOLOGY_SYSTEM_PROMPT = """你是一个专业的知识图谱本体设计专家
             "attributes": []
         }
     ],
-    "analysis_summary": "对文本内容的简要分析说明（中文）"
+    "analysis_summary": "对文本内容的简要分析说明"
 }
 ```