Add demo trading page, trader snapshot service and trading tables

Add trading_symbols, trading_analyses, trading_orders and trading_events.
The new trader service publishes account, position and open-order
snapshots of the Binance demo account to Redis every 3s. The /trading
page shows engine status, start/stop, balances, positions, the symbol
list with angle selection, open orders and the event timeline.

backend/src/alphapulse/models/trading.py

@@ -1,6 +1,8 @@
 from datetime import datetime
+from decimal import Decimal
 
-from sqlalchemy import Boolean, CheckConstraint, DateTime, ForeignKey, LargeBinary, String, func
+from sqlalchemy import BigInteger, Boolean, CheckConstraint, DateTime, ForeignKey, Index, Integer, LargeBinary, Numeric, String, Text, func
+from sqlalchemy.dialects.postgresql import JSONB
 from sqlalchemy.orm import Mapped, mapped_column
 
 from alphapulse.core.db import Base
@@ -22,3 +24,104 @@ class TradingAccount(Base):
     provider_id: Mapped[int | None] = mapped_column(ForeignKey("ai_providers.id", ondelete="SET NULL"))
     reasoning_effort: Mapped[str | None] = mapped_column(String(8))
     updated_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now(), onupdate=func.now())
+
+
+class TradingSymbol(Base):
+    __tablename__ = "trading_symbols"
+
+    symbol: Mapped[str] = mapped_column(String(32), primary_key=True)
+    # short：24h 内平仓；long：12–48h 平仓
+    angle: Mapped[str] = mapped_column(String(8))
+    added_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
+    # 待执行的分析请求：多个触发在执行前合并为一次
+    analysis_requested_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
+    analysis_reasons: Mapped[list[str]] = mapped_column(JSONB, default=list)
+
+
+class TradingAnalysis(Base):
+    """一次模型分析；action=plan 的行同时是一个交易计划，plan_* 等字段记录其生命周期"""
+
+    __tablename__ = "trading_analyses"
+    __table_args__ = (Index("ix_trading_analyses_symbol_started", "symbol", "started_at"),)
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    symbol: Mapped[str] = mapped_column(String(32))
+    angle: Mapped[str] = mapped_column(String(8))
+    reasons: Mapped[list[str]] = mapped_column(JSONB)
+    # 停止状态下的分析只记录计划、不下单
+    dry_run: Mapped[bool] = mapped_column(Boolean)
+    # running / done / failed
+    status: Mapped[str] = mapped_column(String(16), default="running")
+    # plan / keep / exit
+    action: Mapped[str | None] = mapped_column(String(8))
+    # submit_trade_plan 的参数原样保存
+    decision: Mapped[dict | None] = mapped_column(JSONB)
+    # 程序算出的各档数量、风险金额、盈亏比等
+    sizing: Mapped[dict | None] = mapped_column(JSONB)
+    text: Mapped[str | None] = mapped_column(Text)
+    transcript: Mapped[list | None] = mapped_column(JSONB)
+    provider_id: Mapped[int | None] = mapped_column(ForeignKey("ai_providers.id", ondelete="SET NULL"))
+    model: Mapped[str | None] = mapped_column(String(128))
+    reasoning_effort: Mapped[str | None] = mapped_column(String(8))
+    usage: Mapped[dict | None] = mapped_column(JSONB)
+    error: Mapped[str | None] = mapped_column(Text)
+    started_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
+    finished_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
+    # pending（挂单中）/ open（持仓中）/ closed / canceled（未成交即结束）/ replaced（被新计划替换）
+    plan_status: Mapped[str | None] = mapped_column(String(16))
+    valid_until: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
+    first_fill_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
+    close_deadline: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
+    closed_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
+    close_reason: Mapped[str | None] = mapped_column(String(32))
+    # 平仓后的已实现盈亏、手续费
+    result: Mapped[dict | None] = mapped_column(JSONB)
+
+
+class TradingOrder(Base):
+    """订单流水：先写行再发单，clientOrderId / clientAlgoId 为 ap{id}，超时后按它查询而不是换 id 重发"""
+
+    __tablename__ = "trading_orders"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    analysis_id: Mapped[int | None] = mapped_column(ForeignKey("trading_analyses.id"), index=True)
+    symbol: Mapped[str] = mapped_column(String(32), index=True)
+    # entry / tp / stop / close
+    purpose: Mapped[str] = mapped_column(String(8))
+    # 入场或止盈的档位序号，从 0 开始
+    leg: Mapped[int | None] = mapped_column(Integer)
+    # 条件单走 /fapi/v1/algoOrder
+    is_algo: Mapped[bool] = mapped_column(Boolean)
+    side: Mapped[str] = mapped_column(String(4))
+    type: Mapped[str] = mapped_column(String(24))
+    price: Mapped[Decimal | None] = mapped_column(Numeric)
+    trigger_price: Mapped[Decimal | None] = mapped_column(Numeric)
+    quantity: Mapped[Decimal] = mapped_column(Numeric)
+    reduce_only: Mapped[bool] = mapped_column(Boolean)
+    # submitting / new / partially_filled / filled / canceled / expired / rejected / finished / failed
+    status: Mapped[str] = mapped_column(String(16), default="submitting")
+    # orderId 或 algoId
+    exchange_id: Mapped[str | None] = mapped_column(String(32))
+    filled_qty: Mapped[Decimal] = mapped_column(Numeric, default=0)
+    avg_price: Mapped[Decimal | None] = mapped_column(Numeric)
+    error: Mapped[str | None] = mapped_column(Text)
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
+    updated_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now(), onupdate=func.now())
+
+
+class TradingEvent(Base):
+    """只追加的时间线"""
+
+    __tablename__ = "trading_events"
+    __table_args__ = (Index("ix_trading_events_symbol_id", "symbol", "id"),)
+
+    id: Mapped[int] = mapped_column(BigInteger, primary_key=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now())
+    # 账户级事件（启停等）为空
+    symbol: Mapped[str | None] = mapped_column(String(32))
+    analysis_id: Mapped[int | None] = mapped_column(ForeignKey("trading_analyses.id"))
+    kind: Mapped[str] = mapped_column(String(32))
+    # info / warn / error
+    level: Mapped[str] = mapped_column(String(8), default="info")
+    message: Mapped[str] = mapped_column(Text)
+    data: Mapped[dict | None] = mapped_column(JSONB)