feat: add Signal Pydantic schemas

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/app/schemas/signal.py

@@ -0,0 +1,53 @@
+"""
+Signal related Pydantic schemas.
+"""
+from datetime import date, datetime
+from decimal import Decimal
+from typing import Optional, List
+from enum import Enum
+
+from pydantic import BaseModel
+
+from app.schemas.portfolio import FloatDecimal
+
+
+class SignalType(str, Enum):
+    BUY = "buy"
+    SELL = "sell"
+    PARTIAL_SELL = "partial_sell"
+
+
+class SignalStatus(str, Enum):
+    ACTIVE = "active"
+    EXECUTED = "executed"
+    EXPIRED = "expired"
+
+
+class SignalResponse(BaseModel):
+    id: int
+    date: date
+    ticker: str
+    name: Optional[str] = None
+    signal_type: str
+    entry_price: Optional[FloatDecimal] = None
+    target_price: Optional[FloatDecimal] = None
+    stop_loss_price: Optional[FloatDecimal] = None
+    reason: Optional[str] = None
+    status: str
+    created_at: datetime
+
+    class Config:
+        from_attributes = True
+
+
+class ActivePosition(BaseModel):
+    ticker: str
+    name: Optional[str] = None
+    entry_date: date
+    entry_price: FloatDecimal
+    current_price: FloatDecimal
+    shares: int
+    stop_loss_price: FloatDecimal
+    target_price: FloatDecimal
+    pnl_percent: FloatDecimal
+    pnl_amount: FloatDecimal