feat(memory): add session-based chat history and user metadata retrieval

- Add ChatSessionCache to manage chat history per session
- Add SEARCH_USER_METADATA cypher query for retrieving user entity metadata
- Add "str" mode support to StructResponse for raw text extraction
- Add content_str field to MemorySearchResult for pre-formatted content
- Fix sandbox URL by removing hardcoded port
- Add description field to entity search results
- Remove history from UserInput schema, use session_id instead

api/app/repositories/neo4j/cypher_queries.py

@@ -1296,6 +1296,7 @@ RETURN e.id AS id,
        e.name AS name,
        e.end_user_id AS end_user_id,
        e.entity_type AS entity_type,
+       e.description AS description,
        COALESCE(e.activation_value, e.importance_score, 0.5) AS activation_value,
        COALESCE(e.importance_score, 0.5) AS importance_score,
        e.last_access_time AS last_access_time,
@@ -1479,6 +1480,21 @@ ORDER BY score DESC
 LIMIT $limit
 """
 
+SEARCH_USER_METADATA = """
+MATCH (n:ExtractedEntity)
+WHERE (n.end_user_id = $end_user_id AND n.entity_type ='用户')
+RETURN n.description AS description,
+       n.aliases AS aliases,
+       n.anchors AS anchors,
+       n.beliefs_or_stances AS beliefs_or_stances,
+       n.core_facts AS core_facts,
+       n.events AS events,
+       n.goals AS goals,
+       n.interests AS interests,
+       n.relations AS relations,
+       n.traits AS traits
+"""
+
 FULLTEXT_QUERY_CYPHER_MAPPING = {
     Neo4jNodeType.STATEMENT: SEARCH_STATEMENTS_BY_KEYWORD,
     Neo4jNodeType.EXTRACTEDENTITY: SEARCH_ENTITIES_BY_NAME_OR_ALIAS,