dashboard: stale-session alarm banner + rvol_tod in armed triggers

The 07-21 morning outage (loop booted post-EOD on the 20th, survived
midnight, silently blocked every entry while signals went READY) had zero
UI surface. New query_loop_session projection parses the live session id's
embedded date; a red banner fires when it isn't today's — the exact day-2
poison signature — telling the operator to restart the loop. Armed
Triggers rows now also show rvol_tod (the arming signal since 5597250)
next to legacy rvol.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/unit/storage/test_interactive_projections.py

@@ -282,3 +282,28 @@ def test_daily_performance_curve_trading_days_only():
     assert days[1]["day_pnl"] == -200.0 and days[1]["cum_pnl"] == -100.0
     assert days[1]["trades"] == 2 and days[1]["win_rate"] == 0.5
     store.close()
+
+
+def test_loop_session_stale_detection(store):
+    """A paper session whose embedded date != today must flag stale — the day-2
+    silent entry-block signature (loop booted post-EOD, survived midnight)."""
+    from storage.event_schema import ModuleTickEvent
+    from storage.projections import query_loop_session
+
+    def _tick(cid):
+        store.emit(ModuleTickEvent(
+            timestamp=datetime.now(), mode=EventMode.PAPER,
+            correlation_id=cid, message="tick",
+            module="triggers", stage="snapshot", duration_ms=0.0,
+            input_count=0, output_count=0, metrics={}, errors=[]))
+
+    _tick("paper-2020-01-02-abc123")
+    s = query_loop_session(store)
+    assert s["session_id"] == "paper-2020-01-02-abc123"
+    assert s["session_date"] == "2020-01-02"
+    assert s["stale"] is True
+
+    today = datetime.now().strftime("%Y-%m-%d")
+    _tick(f"paper-{today}-def456")
+    s = query_loop_session(store)
+    assert s["session_date"] == today and s["stale"] is False