Add amplitude filter as first open gate for 永期 hedge.

Reuse OO amplitude settings (default off); Plan shows index/HL when filtering.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/strategy/engine.py

@@ -1047,6 +1047,14 @@ class StrategyEngine:
                 )
                 return
         if pick is None:
+            amp_fail = None
+            try:
+                amp_fail = get_session().amplitude_gate_fail_reason()
+            except Exception:
+                amp_fail = None
+            if amp_fail:
+                self._set_state(last_error=amp_fail)
+                return
             try:
                 from .auto_usdc import preview_capacity_for_convert
                 from .open_capacity import funds_gate_blocks