fix: cast json_query to VARCHAR for StarRocks DISTINCT, add sku_color to API,...

fix: cast json_query to VARCHAR for StarRocks DISTINCT, add sku_color to API, merge knowledge tool to 1 query

backend/agent/tools/brand_knowledge_tool.py

@@ -37,14 +37,14 @@ async def canifa_knowledge_search(query: str) -> str:
         # 2. SINGLE QUERY: Tìm top K chunks → lấy full document theo title (1 round-trip)
         sql = f"""
             WITH top_chunks AS (
-                SELECT json_query(metadata, '$.title') AS title
+                SELECT CAST(json_query(metadata, '$.title') AS VARCHAR) AS title
                 FROM shared_source.chatbot_rsa_knowledge
                 ORDER BY approx_cosine_similarity(embedding, {v_str}) DESC
                 LIMIT {TOP_K_CHUNKS}
             )
             SELECT k.content, k.metadata
             FROM shared_source.chatbot_rsa_knowledge k
-            WHERE json_query(k.metadata, '$.title') IN (
+            WHERE CAST(json_query(k.metadata, '$.title') AS VARCHAR) IN (
                 SELECT DISTINCT title FROM top_chunks WHERE title IS NOT NULL
             )
         """