fix: align MOSProduct._build_system_prompt signature with MOSCore

- Fix TypeError when calling MOSProduct.chat() method
- MOSCore.chat() expects _build_system_prompt(memories, base_prompt=...)
- MOSProduct._build_system_prompt had incompatible signature (user_id, memories)
- Updated signature to match parent class interface
- Removed unused user_id parameter from method

Author: muzzlol

src/memos/mem_os/product.py

@@ -327,7 +327,7 @@ def _get_or_create_user_config(
 
         return self._create_user_config(user_id, user_config)
 
-    def _build_system_prompt(self, user_id: str, memories_all: list[TextualMemoryItem]) -> str:
+    def _build_system_prompt(self, memories_all: list[TextualMemoryItem], base_prompt: str | None = None) -> str:
         """
         Build custom system prompt for the user with memory references.
 
@@ -759,7 +759,7 @@ def chat_with_references(
             memories_list = memories_result[0]["memories"]
 
         # Build custom system prompt with relevant memories
-        system_prompt = self._build_system_prompt(user_id, memories_list)
+        system_prompt = self._build_system_prompt(memories_list, base_prompt=None)
 
         # Get chat history
         target_user_id = user_id if user_id is not None else self.user_id