feat: database models and alembic migrations — all tables per design

- shared/db.py: async engine + session factory
- shared/models/base.py: DeclarativeBase + TimestampMixin
- shared/models/trading.py: Strategy, Signal, Trade, Position, StrategyWeightHistory
- shared/models/news.py: Article, ArticleSentiment
- shared/models/learning.py: TradeOutcome, LearningAdjustment
- shared/models/auth.py: User, UserCredential
- shared/models/timeseries.py: MarketData, PortfolioSnapshot, StrategyMetric
- Alembic async env.py with initial migration including TimescaleDB hypertables
- 21 model tests covering enums, instantiation, metadata registration

shared/models/trading.py

@@ -0,0 +1,137 @@
+"""Trading domain models: Strategy, Signal, Trade, Position, StrategyWeightHistory."""
+
+import enum
+import uuid
+
+from sqlalchemy import Boolean, Float, ForeignKey, String, Text
+from sqlalchemy.dialects.postgresql import JSON, UUID
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from shared.models.base import Base, TimestampMixin
+
+
+# ---------------------------------------------------------------------------
+# Enums
+# ---------------------------------------------------------------------------
+
+class TradeSide(str, enum.Enum):
+    BUY = "BUY"
+    SELL = "SELL"
+
+
+class TradeStatus(str, enum.Enum):
+    PENDING = "PENDING"
+    FILLED = "FILLED"
+    CANCELLED = "CANCELLED"
+    REJECTED = "REJECTED"
+
+
+class SignalDirection(str, enum.Enum):
+    LONG = "LONG"
+    SHORT = "SHORT"
+    NEUTRAL = "NEUTRAL"
+
+
+# ---------------------------------------------------------------------------
+# Models
+# ---------------------------------------------------------------------------
+
+class Strategy(TimestampMixin, Base):
+    __tablename__ = "strategies"
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    name: Mapped[str] = mapped_column(String(255), unique=True, nullable=False)
+    description: Mapped[str | None] = mapped_column(Text, nullable=True)
+    current_weight: Mapped[float] = mapped_column(Float, nullable=False, default=0.333)
+    active: Mapped[bool] = mapped_column(Boolean, default=True, nullable=False)
+
+    # Relationships
+    trades: Mapped[list["Trade"]] = relationship(back_populates="strategy")
+    signals: Mapped[list["Signal"]] = relationship(back_populates="strategy", foreign_keys="Signal.strategy_id", viewonly=True)
+    weight_history: Mapped[list["StrategyWeightHistory"]] = relationship(back_populates="strategy")
+
+
+class Signal(TimestampMixin, Base):
+    __tablename__ = "signals"
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    ticker: Mapped[str] = mapped_column(String(20), nullable=False, index=True)
+    direction: Mapped[SignalDirection] = mapped_column(nullable=False)
+    strength: Mapped[float] = mapped_column(Float, nullable=False)
+    strategy_sources: Mapped[dict | None] = mapped_column(JSON, nullable=True)
+    sentiment_score: Mapped[float | None] = mapped_column(Float, nullable=True)
+    acted_on: Mapped[bool] = mapped_column(Boolean, default=False, nullable=False)
+    strategy_id: Mapped[uuid.UUID | None] = mapped_column(
+        UUID(as_uuid=True), ForeignKey("strategies.id"), nullable=True
+    )
+
+    # Relationships
+    strategy: Mapped[Strategy | None] = relationship(back_populates="signals", foreign_keys=[strategy_id])
+    trades: Mapped[list["Trade"]] = relationship(back_populates="signal")
+
+
+class Trade(TimestampMixin, Base):
+    __tablename__ = "trades"
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    ticker: Mapped[str] = mapped_column(String(20), nullable=False, index=True)
+    side: Mapped[TradeSide] = mapped_column(nullable=False)
+    qty: Mapped[float] = mapped_column(Float, nullable=False)
+    price: Mapped[float] = mapped_column(Float, nullable=False)
+    timestamp: Mapped[str | None] = mapped_column(String, nullable=True)
+    strategy_id: Mapped[uuid.UUID | None] = mapped_column(
+        UUID(as_uuid=True), ForeignKey("strategies.id"), nullable=True
+    )
+    signal_id: Mapped[uuid.UUID | None] = mapped_column(
+        UUID(as_uuid=True), ForeignKey("signals.id"), nullable=True
+    )
+    status: Mapped[TradeStatus] = mapped_column(nullable=False, default=TradeStatus.PENDING)
+    pnl: Mapped[float | None] = mapped_column(Float, nullable=True)
+
+    # Relationships
+    strategy: Mapped[Strategy | None] = relationship(back_populates="trades")
+    signal: Mapped[Signal | None] = relationship(back_populates="trades")
+    outcome: Mapped["TradeOutcome | None"] = relationship(
+        "TradeOutcome", back_populates="trade", uselist=False
+    )
+
+
+class Position(TimestampMixin, Base):
+    __tablename__ = "positions"
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    ticker: Mapped[str] = mapped_column(String(20), unique=True, nullable=False)
+    qty: Mapped[float] = mapped_column(Float, nullable=False)
+    avg_entry: Mapped[float] = mapped_column(Float, nullable=False)
+    unrealized_pnl: Mapped[float | None] = mapped_column(Float, nullable=True)
+    stop_loss: Mapped[float | None] = mapped_column(Float, nullable=True)
+    take_profit: Mapped[float | None] = mapped_column(Float, nullable=True)
+
+
+class StrategyWeightHistory(TimestampMixin, Base):
+    __tablename__ = "strategy_weight_history"
+
+    id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True), primary_key=True, default=uuid.uuid4
+    )
+    strategy_id: Mapped[uuid.UUID] = mapped_column(
+        UUID(as_uuid=True), ForeignKey("strategies.id"), nullable=False
+    )
+    old_weight: Mapped[float] = mapped_column(Float, nullable=False)
+    new_weight: Mapped[float] = mapped_column(Float, nullable=False)
+    reason: Mapped[str | None] = mapped_column(String(500), nullable=True)
+
+    # Relationships
+    strategy: Mapped[Strategy] = relationship(back_populates="weight_history")
+
+
+# Avoid circular import — TradeOutcome is defined in learning.py
+from shared.models.learning import TradeOutcome  # noqa: E402, F401