add dashboard apis

app/chain/dashboard.py

@@ -0,0 +1,13 @@
+from app import schemas
+from app.chain import ChainBase
+
+
+class DashboardChain(ChainBase):
+    """
+    各类仪表板统计处理链
+    """
+    def media_statistic(self) -> schemas.Statistic:
+        """
+        媒体数量统计
+        """
+        return self.run_module("media_statistic")