feat: near-close scan schedule and distinct-day gate reset

Move the only qualifying R:R scan to 15:30 ET with chained Telegram alerts,
put outcome eval after a final-bar OHLCV fetch, enforce NY trading-day
requalify semantics, stamp paper trades fill_mode=near_close, and migrate
stored schedule_* keys to America/New_York.

app/models/paper_trade.py

@@ -46,3 +46,6 @@ class PaperTrade(Base):
     reentry_gate_requalified_at: Mapped[datetime | None] = mapped_column(
         DateTime(timezone=True), nullable=True
     )
+    # Execution era for forward vs backtest comparison:
+    # null/legacy = pre-cutover morning-scan, "near_close" = post near-close cutover.
+    fill_mode: Mapped[str | None] = mapped_column(String(20), nullable=True)