feat: 重构数据库导入路径，移除旧的数据库模块并添加新的数据库实现

src/chat/memory_system/Hippocampus.py

@@ -10,7 +10,7 @@ import jieba
 import networkx as nx
 import numpy as np
 from collections import Counter
-from ...common.database import db
+from ...common.database.database import db
 from ...chat.models.utils_model import LLMRequest
 from src.common.logger_manager import get_logger
 from src.chat.memory_system.sample_distribution import MemoryBuildScheduler  # 分布生成器