refactor(flask_server): 多项优化重构

优化内容：

1. fetch_with_adj → fetch(adj=adj)
   - _fetch_full_data_cached 使用 fetch(adj=adj) 替代 fetch_with_adj

2. 加密货币分支添加 adj 参数
   - fetch_data_with_ttl 中加密货币调用添加 adj='raw'

3. ETF 净值溢价率逻辑抽取
   - 新增 build_premium_result() 函数
   - get_ohlcv 和 get_etf_nav 使用该函数，减少 42 行重复代码

4. SSH 配置信息增强
   - ssh_status 改为 ssh 对象，包含更多详细信息
   - 添加 required_types（需要 SSH 的资产类型列表）

代码行数：减少约 40 行重复代码

datasource/flask_server.py

@@ -151,8 +151,8 @@ def _fetch_full_data_cached(code: str, today: str, adj: str = 'raw') -> Optional
     
     try:
         with f:
-            # 使用 fetch_with_adj 获取数据（支持复权）
-            df = f.fetch_with_adj(code, DEFAULT_START_DATE, today, adj)
+            # 使用 fetch(adj=adj) 获取数据（支持复权）
+            df = f.fetch(code, DEFAULT_START_DATE, today, adj)
         
         if df is None or len(df) == 0:
             return None
@@ -276,7 +276,8 @@ def fetch_data_with_ttl(
         f = get_fetcher()
         try:
             with f:
-                df = f.fetch(code, start, end, timeframe=timeframe)
+                # 加密货币仅支持 adj='raw'
+                df = f.fetch(code, start, end, adj='raw', timeframe=timeframe)
             if df is None or len(df) == 0:
                 return None, False
             result = dataframe_to_json(df, asset_type.value)
@@ -469,6 +470,43 @@ def get_default_dates() -> Tuple[str, str]:
     return start.strftime('%Y-%m-%d'), end.strftime('%Y-%m-%d')
 
 
+def build_premium_result(premium_series: pd.Series) -> Dict:
+    """
+    构建溢价率返回结果
+    
+    Args:
+        premium_series: 溢价率序列（索引为日期）
+    
+    Returns:
+        包含 premium_series, latest_premium, premium_date, premium_stats 的字典
+    """
+    if premium_series is None or len(premium_series) == 0:
+        return {}
+    
+    # 转换为日期-溢价率列表
+    premium_data = [
+        {"date": date.strftime('%Y-%m-%d'), "premium": round(premium, 6)}
+        for date, premium in premium_series.items()
+    ]
+    
+    # 最新溢价率
+    latest_premium = premium_series.iloc[-1]
+    latest_date = premium_series.index[-1].strftime('%Y-%m-%d')
+    
+    return {
+        "premium_series": premium_data,
+        "latest_premium": round(latest_premium, 6),
+        "premium_date": latest_date,
+        "premium_stats": {
+            "mean": round(premium_series.mean(), 6),
+            "std": round(premium_series.std(), 6),
+            "min": round(premium_series.min(), 6),
+            "max": round(premium_series.max(), 6),
+            "median": round(premium_series.median(), 6),
+        },
+    }
+
+
 # ============================================================
 # API 路由
 # ============================================================
@@ -524,7 +562,12 @@ def index():
             "crypto": ["BTC", "ETH"],
         },
         "cache_config": get_cache_info(),
-        "ssh_status": "enabled" if ssh_config and ssh_config.get('enabled') else "disabled",
+        "ssh": {
+            "status": "enabled" if ssh_config and ssh_config.get('enabled') else "disabled",
+            "host": ssh_config.get('host', '') if ssh_config else '',
+            "required_types": [t.value for t in UniversalDataFetcher.SSH_REQUIRED_TYPES],
+            "description": "港美股/加密货币数据获取需要 SSH 隧道",
+        },
     })
 
 
@@ -700,28 +743,10 @@ def get_ohlcv():
             if nav_df is not None and len(nav_df) > 0:
                 result['nav'] = dataframe_to_json(nav_df)
             
-            # 添加溢价率序列
-            if premium_series is not None and len(premium_series) > 0:
-                premium_data = [
-                    {"date": date.strftime('%Y-%m-%d'), "premium": round(premium, 6)}
-                    for date, premium in premium_series.items()
-                ]
-                result['premium_series'] = premium_data
-                
-                # 最新溢价率
-                latest_premium = premium_series.iloc[-1]
-                latest_date = premium_series.index[-1].strftime('%Y-%m-%d')
-                result['latest_premium'] = round(latest_premium, 6)
-                result['premium_date'] = latest_date
-                
-                # 溢价率统计
-                result['premium_stats'] = {
-                    "mean": round(premium_series.mean(), 6),
-                    "std": round(premium_series.std(), 6),
-                    "min": round(premium_series.min(), 6),
-                    "max": round(premium_series.max(), 6),
-                    "median": round(premium_series.median(), 6),
-                }
+            # 添加溢价率数据（使用抽取的函数）
+            premium_result = build_premium_result(premium_series)
+            if premium_result:
+                result.update(premium_result)
         except Exception as e:
             # 净值获取失败不影响主数据返回
             result['nav_error'] = str(e)
@@ -840,30 +865,10 @@ def get_etf_nav():
             "nav": dataframe_to_json(nav_df) if nav_df else {"data": [], "count": 0},
         }
         
-        # 添加历史溢价率序列
-        if premium_series is not None and len(premium_series) > 0:
-            # 转换为日期-溢价率列表
-            premium_data = [
-                {"date": date.strftime('%Y-%m-%d'), "premium": round(premium, 6)}
-                for date, premium in premium_series.items()
-            ]
-            result['premium_series'] = premium_data
-            
-            # 最新溢价率
-            latest_premium = premium_series.iloc[-1]
-            latest_date = premium_series.index[-1].strftime('%Y-%m-%d')
-            result['latest_premium'] = round(latest_premium, 6)
-            result['premium_date'] = latest_date
-            
-            # 溢价率统计
-            result['premium_stats'] = {
-                "mean": round(premium_series.mean(), 6),
-                "std": round(premium_series.std(), 6),
-                "min": round(premium_series.min(), 6),
-                "max": round(premium_series.max(), 6),
-                "median": round(premium_series.median(), 6),
-            }
-        
+        # 添加溢价率数据（使用抽取的函数）
+        premium_result = build_premium_result(premium_series)
+        if premium_result:
+            result.update(premium_result)
         
         return jsonify(result)