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

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

tests/test_zh_cache_integration.py

@@ -0,0 +1,56 @@
+"""Integration test: committed zh cache files load cleanly onto real RAGAS metric instances."""
+
+from pathlib import Path
+
+from rag_eval.metrics.judge_prompts import CACHE_ROOT, METRIC_PROMPT_ATTRS
+
+
+def test_zh_cache_files_all_present():
+    """All expected zh cache files are committed and present on disk."""
+    zh_dir = CACHE_ROOT / "zh"
+    for metric, attrs in METRIC_PROMPT_ATTRS.items():
+        for attr in attrs:
+            path = zh_dir / f"{metric}__{attr}.json"
+            assert path.exists(), f"Missing committed cache: {path}"
+
+
+def test_zh_cache_loads_onto_real_metrics():
+    """Localize all registry metrics to zh — zero skips, zero errors."""
+    from unittest.mock import MagicMock
+    from ragas.llms.base import InstructorBaseRagasLLM
+    from ragas.embeddings.base import BaseRagasEmbedding
+    from rag_eval.metrics.factory import build_metric_registry
+    from rag_eval.metrics.judge_prompts import localize_pipeline_prompts, reset_cache
+
+    reset_cache()
+    llm = MagicMock(spec=InstructorBaseRagasLLM)
+    emb = MagicMock(spec=BaseRagasEmbedding)
+    registry = build_metric_registry(llm, emb)
+    report = localize_pipeline_prompts(registry, "zh")
+
+    expected_count = sum(len(attrs) for attrs in METRIC_PROMPT_ATTRS.values())
+    assert len(report.applied) == expected_count, (
+        f"Expected {expected_count} applied, got {len(report.applied)}; "
+        f"skipped={report.skipped}, warnings={report.warnings}"
+    )
+    assert not report.skipped, f"Unexpected skips: {report.skipped}"
+
+
+def test_zh_cache_instructions_are_chinese():
+    """After localization, faithfulness instruction starts with Chinese characters."""
+    from unittest.mock import MagicMock
+    from ragas.llms.base import InstructorBaseRagasLLM
+    from ragas.embeddings.base import BaseRagasEmbedding
+    from rag_eval.metrics.factory import build_metric_registry
+    from rag_eval.metrics.judge_prompts import localize_pipeline_prompts, reset_cache
+
+    reset_cache()
+    llm = MagicMock(spec=InstructorBaseRagasLLM)
+    emb = MagicMock(spec=BaseRagasEmbedding)
+    registry = build_metric_registry(llm, emb)
+    localize_pipeline_prompts(registry, "zh")
+
+    instr = registry["faithfulness"].statement_generator_prompt.instruction
+    # Chinese instruction should contain at least one CJK character.
+    has_chinese = any("\u4e00" <= ch <= "\u9fff" for ch in instr)
+    assert has_chinese, f"Instruction does not contain Chinese: {instr[:60]}"