feat: initial commit - EvoTraders project

量化交易多智能体系统，包含：
- 分析师、投资组合经理、风险经理等智能体
- 股票分析、投资组合管理、风险控制工具
- React 前端界面
- FastAPI 后端服务

Co-Authored-By: Claude <noreply@anthropic.com>

backend/config/data_config.py

@@ -0,0 +1,82 @@
+# -*- coding: utf-8 -*-
+"""
+Centralized Data Source Configuration
+
+Auto-detects and manages data source based on available API keys.
+Priority: FINNHUB_API_KEY > FINANCIAL_DATASETS_API_KEY
+"""
+import os
+from dataclasses import dataclass
+from typing import Literal, Optional
+
+DataSource = Literal["finnhub", "financial_datasets"]
+
+
+@dataclass
+class DataSourceConfig:
+    """Immutable data source configuration"""
+
+    source: DataSource
+    api_key: str
+
+
+# Module-level cache for the resolved configuration
+_config_cache: Optional[DataSourceConfig] = None
+
+
+def _resolve_config() -> DataSourceConfig:
+    """
+    Resolve data source configuration based on available API keys.
+
+    Priority:
+    1. FINNHUB_API_KEY (if set)
+    2. FINANCIAL_DATASETS_API_KEY (if set)
+    3. Raises error if neither is available
+    """
+    # Check for Finnhub API key first (higher priority)
+    finnhub_key = os.getenv("FINNHUB_API_KEY")
+    if finnhub_key:
+        return DataSourceConfig(source="finnhub", api_key=finnhub_key)
+
+    # Fallback to Financial Datasets API
+    fd_key = os.getenv("FINANCIAL_DATASETS_API_KEY")
+    if fd_key:
+        return DataSourceConfig(source="financial_datasets", api_key=fd_key)
+
+    # No API key available
+    raise ValueError(
+        "No API key found. Please set either FINNHUB_API_KEY or "
+        "FINANCIAL_DATASETS_API_KEY in your .env file.",
+    )
+
+
+def get_config() -> DataSourceConfig:
+    """
+    Get the resolved data source configuration (cached).
+
+    Returns:
+        DataSourceConfig with source and api_key
+
+    Raises:
+        ValueError: If no API key is configured
+    """
+    global _config_cache
+    if _config_cache is None:
+        _config_cache = _resolve_config()
+    return _config_cache
+
+
+def get_data_source() -> DataSource:
+    """Get the configured data source name."""
+    return get_config().source
+
+
+def get_api_key() -> str:
+    """Get the API key for the configured data source."""
+    return get_config().api_key
+
+
+def reset_config() -> None:
+    """Reset the cached configuration (useful for testing)."""
+    global _config_cache
+    _config_cache = None