feat: 下沉知识库检索编排能力

- 新增 rag retrieval 核心协议、RRF 融合与相关度归一化

- 支持关键词检索按 knowledgeId 过滤并补充 ES/Lucene 单测

- 扩展 KnowledgeNode 检索模式与 Milvus 检索参数透传

easy-agents-search-engine/easy-agents-search-engine-es/src/test/java/com/easyagents/engine/es/ElasticSearcherQueryBuilderTest.java

@@ -0,0 +1,54 @@
+package com.easyagents.engine.es;
+
+import co.elastic.clients.elasticsearch.core.SearchRequest;
+import com.easyagents.core.document.Document;
+import com.easyagents.search.engine.service.KeywordSearchMetadataKeys;
+import com.easyagents.search.engine.service.KeywordSearchRequest;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.Map;
+
+public class ElasticSearcherQueryBuilderTest {
+
+    @Test
+    public void shouldBuildSearchRequestWithMultiMatchAndKnowledgeFilter() {
+        ElasticSearcher searcher = new ElasticSearcher(config());
+        KeywordSearchRequest request = KeywordSearchRequest.of("客服", 5);
+        request.setKnowledgeId("100");
+
+        SearchRequest searchRequest = searcher.buildSearchRequest(request);
+
+        Assert.assertEquals(5, searchRequest.size().intValue());
+        Assert.assertNotNull(searchRequest.query().bool());
+        Assert.assertEquals(1, searchRequest.query().bool().must().size());
+        Assert.assertNotNull(searchRequest.query().bool().must().get(0).multiMatch());
+        Assert.assertEquals(2, searchRequest.query().bool().must().get(0).multiMatch().fields().size());
+        Assert.assertEquals(1, searchRequest.query().bool().filter().size());
+        Assert.assertEquals("knowledgeId", searchRequest.query().bool().filter().get(0).term().field());
+    }
+
+    @Test
+    public void shouldExtractKnowledgeIdToTopLevelSource() {
+        ElasticSearcher searcher = new ElasticSearcher(config());
+        Document document = new Document();
+        document.setId("1");
+        document.setTitle("title");
+        document.setContent("content");
+        document.addMetadata(KeywordSearchMetadataKeys.KNOWLEDGE_ID, "100");
+
+        Map<String, Object> source = searcher.buildSource(document);
+
+        Assert.assertEquals("100", source.get(KeywordSearchMetadataKeys.KNOWLEDGE_ID));
+        Assert.assertTrue(source.get("metadataMap") instanceof Map);
+    }
+
+    private ESConfig config() {
+        ESConfig config = new ESConfig();
+        config.setHost("http://127.0.0.1:9200");
+        config.setUserName("elastic");
+        config.setPassword("elastic");
+        config.setIndexName("easyflow");
+        return config;
+    }
+}