feat(portfolios): allow unassigned strategy creation

app/api/v1_portfolios.py

@@ -186,11 +186,13 @@ def create_portfolio_v1(
             )
 
         name = body.name or f"{body.broker}-{body.asset_id[:8]}"
-        strategy_set = repo.get_strategy_set(body.strategy_id)
-        if strategy_set is None:
-            raise StrategyNotFoundError(f"strategy not found: {body.strategy_id}")
-        if strategy_set.status != "active":
-            raise StrategyInactiveError(f"strategy is inactive: {body.strategy_id}")
+        strategy_set = None
+        if body.strategy_id is not None:
+            strategy_set = repo.get_strategy_set(body.strategy_id)
+            if strategy_set is None:
+                raise StrategyNotFoundError(f"strategy not found: {body.strategy_id}")
+            if strategy_set.status != "active":
+                raise StrategyInactiveError(f"strategy is inactive: {body.strategy_id}")
 
         _require_valid_daemon_uuid(body.managed_by_daemon_id)
 
@@ -205,8 +207,8 @@ def create_portfolio_v1(
             asset_quantity=body.asset_quantity,
             asset_price=body.asset_price,
             profit_buffer=body.profit_buffer,
-            active_strategy_id=strategy_set.id,
-            avabile_strategies=[strategy_set.id],
+            active_strategy_id=strategy_set.id if strategy_set is not None else None,
+            avabile_strategies=[strategy_set.id] if strategy_set is not None else None,
             managed_by_daemon_id=body.managed_by_daemon_id,
         )
     except HTTPException: