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/schemas/memory_agent_schema.py

@@ -1,14 +1,15 @@
+import uuid
 from abc import ABC
 from typing import Optional
 
-from pydantic import BaseModel
+from pydantic import BaseModel, Field
 
 
 class UserInput(BaseModel):
     message: str
-    history: list[dict]
     search_switch: str
     end_user_id: str
+    session_id: uuid.UUID = Field(default_factory=uuid.uuid4)
     config_id: Optional[str] = None