Add demo trading executor and analysis scheduling (plan 3 C4)

- Executor reconciles each symbol to its desired orders: journaled ap{id}
  client ids, reduce-only quantity stop placed before entries, make-before-
  break stop moves, breakeven after TP1, orphan cancel, -2021 market close
- Plan lifecycle: proposed plans are adopted only if the position is
  unchanged; holding-mode plans may only tighten the stop
- Program rules: time stop, short-term invalidation close, long-term 4h
  review, reevaluate conditions, takeover of unmanaged positions
- Trigger and routine analysis scheduling with a 10 min gap, daily cap and
  bounded retries
- Plan endpoint and plan status, fills and countdowns on the trading page

backend/src/alphapulse/models/trading.py

@@ -69,7 +69,8 @@ class TradingAnalysis(Base):
     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）
+    # proposed（待执行器采纳）/ pending（挂单中）/ open（持仓中）/ closing（平仓中）/ closed / canceled（未成交即结束）
+    # / replaced（被新计划替换）/ stale（采纳前持仓已变，作废）/ applied（exit 决定已执行）
     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))