docs(README): 更新项目说明文档，完善架构与启动指南

- 调整 CLAUDE.md 内容，增加使用指导和架构概览
- 补充微服务启动说明及单服务启动命令
- 明确 Gateway 服务器四阶段启动流程和职责划分
- 细化后端目录结构说明，补充主要文件职责描述
- 新增系统分层结构图，优化整体架构理解
- 更新 .gitignore，添加 runs 目录忽略规则
- 同步 .omc 相关状态文件，更新项目状态跟踪信息

backend/data/market_store.py

@@ -9,7 +9,7 @@ import os
 import sqlite3
 from datetime import datetime, timezone
 from pathlib import Path
-from typing import Any, Iterable
+from typing import Any, Iterable, Optional
 
 
 SCHEMA = """
@@ -147,12 +147,30 @@ def _utc_timestamp() -> str:
 
 
 class MarketStore:
-    """SQLite-backed market research warehouse."""
+    """SQLite-backed market research warehouse. Use get_instance() for the singleton."""
+
+    _instance: Optional["MarketStore"] = None
+
+    def __new__(cls, db_path: Path | None = None) -> "MarketStore":
+        if cls._instance is not None:
+            if db_path is None or cls._instance.db_path == Path(db_path or get_market_db_path()):
+                return cls._instance
+        instance = super().__new__(cls)
+        cls._instance = instance
+        return instance
 
     def __init__(self, db_path: Path | None = None):
+        if getattr(self, "_initialized", False):
+            return
         self.db_path = Path(db_path or get_market_db_path())
         self.db_path.parent.mkdir(parents=True, exist_ok=True)
         self._init_db()
+        self._initialized = True
+
+    @classmethod
+    def get_instance(cls, db_path: Path | None = None) -> "MarketStore":
+        """Get the MarketStore singleton instance."""
+        return cls(db_path)
 
     def _connect(self) -> sqlite3.Connection:
         conn = sqlite3.connect(self.db_path)