rebuild(stage-8): deliver market insight workspaces

next/backend/data/providers/base.py

@@ -28,3 +28,15 @@ class MarketDataProvider(Protocol):
     ) -> dict[str, ProviderResult | dict[str, Any]]: ...
 
     def sector_members(self, representative: str, trade_date: str) -> ProviderResult: ...
+
+    def market_insight(
+        self,
+        kind: str,
+        trade_date: str,
+        previous_trade_date: str = "",
+        identifier: str = "",
+    ) -> dict[str, ProviderResult | None]: ...
+
+    def realtime_snapshots(
+        self, identifiers: tuple[str, ...], start_time: str, end_time: str
+    ) -> ProviderResult: ...