refactor QMT client and optimize API

py-client/libs/grid_take_profit.py

@@ -20,7 +20,7 @@ class GridState(str, Enum):
     STEADY = "steady"     # 仍处于当前峰值网格，继续持有
 
 
-@dataclass(frozen=True)
+@dataclass(frozen=True, slots=True)
 class GridObservation:
     """一次网格观察的不可变结果。"""
 

py-client/libs/signal.py

@@ -4,12 +4,12 @@ import secrets
 from .http import get_json
 
 
-@dataclass
+@dataclass(slots=True)
 class SignalItem:
     signal_key: str = ""; code: str = ""; name: str = ""; desc: str = ""; last_close: float = 0
     tech_indicator: dict[str, float] = field(default_factory=dict)
 
-@dataclass
+@dataclass(slots=True)
 class SignalResult:
     code: str = ""; total: int = 0; updated: str = ""; data: dict[str, SignalItem] = field(default_factory=dict); message: str = ""