add paper trading: mark a setup as taken, track open P&L, sell

New paper_trades table (migration 007) + service/router. "Mark as taken" on each
setup card (shares prefilled from position sizing, entry from current price, both
editable) records a simulated trade. Overview gains an Open Trades table that
marks each position to the latest close — P&L in $, %, and R-multiples — with a
total unrealized P&L footer and a Sell button to close at the current price.
Closed trades are retained for future realized-P&L reporting.

Deploy: alembic upgrade (new paper_trades table).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/models/__init__.py

@@ -9,6 +9,7 @@ from app.models.trade_setup import TradeSetup
 from app.models.watchlist import WatchlistEntry
 from app.models.settings import SystemSetting, IngestionProgress
 from app.models.alert import AlertLog
+from app.models.paper_trade import PaperTrade
 
 __all__ = [
     "Ticker",
@@ -24,4 +25,5 @@ __all__ = [
     "SystemSetting",
     "IngestionProgress",
     "AlertLog",
+    "PaperTrade",
 ]

app/models/paper_trade.py

@@ -0,0 +1,36 @@
+from datetime import datetime
+
+from sqlalchemy import DateTime, Float, ForeignKey, String
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.database import Base
+
+
+class PaperTrade(Base):
+    """A simulated ('taken') trade for paper trading.
+
+    Captured from a setup at the moment the user marks it taken: direction,
+    entry, size, stop and target. Open trades are marked-to-market against the
+    latest close; closing records the exit price and time.
+    """
+
+    __tablename__ = "paper_trades"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    user_id: Mapped[int] = mapped_column(
+        ForeignKey("users.id", ondelete="CASCADE"), nullable=False
+    )
+    ticker_id: Mapped[int] = mapped_column(
+        ForeignKey("tickers.id", ondelete="CASCADE"), nullable=False
+    )
+    direction: Mapped[str] = mapped_column(String(10), nullable=False)
+    entry_price: Mapped[float] = mapped_column(Float, nullable=False)
+    shares: Mapped[float] = mapped_column(Float, nullable=False)
+    stop_loss: Mapped[float] = mapped_column(Float, nullable=False)
+    target: Mapped[float] = mapped_column(Float, nullable=False)
+    status: Mapped[str] = mapped_column(String(10), nullable=False, default="open")
+    opened_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), default=datetime.utcnow, nullable=False
+    )
+    close_price: Mapped[float | None] = mapped_column(Float, nullable=True)
+    closed_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)