Add committed zh judge-prompt cache + enable in Siemens scenarios + docs

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

scenarios/offline/siemens-pdf-offline-smoke.yaml

@@ -4,6 +4,8 @@ app_adapter: null
 dataset: ../../datasets/normalized/siemens_pdf_offline_smoke.csv
 judge_model: deepseek-v4-flash
 embedding_model: text-embedding-v3
+# 使用中文评判 prompt 以提升对中文语料的判定一致性（架构设计 §10.5）
+judge_language: zh
 metrics:
   - faithfulness
   - answer_relevancy

scenarios/online/siemens-pdf-question-bank-online.yaml

@@ -3,6 +3,8 @@ mode: online
 dataset: ../../datasets/raw/generated/siemens-pdf-question-bank.csv
 judge_model: deepseek-v4-flash
 embedding_model: text-embedding-v3
+# 使用中文评判 prompt 以提升对中文语料的判定一致性（架构设计 §10.5）
+judge_language: zh
 optimization_advisor: true
 metrics:
 - faithfulness