malkhut: REQUOTE as proper CANCEL_REPLACE primitive + action_menu metadata

REQUOTE is now distinct from QUOTE:
  QUOTE: PLACE new order (no existing to cancel)
  REQUOTE: CANCEL_REPLACE existing + place new (immediate)
  CHASE: PLACE with short TTL (auto-cancel retry)
  CANCEL: Remove existing order

action_menu generates REQUOTE with metadata={'requote': True} for existing orders.
DSL REQUOTE produces CANCEL_REPLACE when existing order, falls back to PLACE.

All 800+ tests pass.

MALKHUT/malkhut/planner/action_menu.py

@@ -98,6 +98,7 @@ def build_our_actions(
                 price_ticks_from_best=offset, qty_fraction=0.25,
                 ttl_ms=params.passive_ttl_ms, cancel_order_id=oo.client_order_id,
                 post_only=intent.prefer_maker, reduce_only=intent.reduce_only,
+                metadata={"requote": True, "requote_offset": offset},
             ))
 
     # Passive quote placements

MALKHUT/malkhut/training/dsl.py

@@ -706,10 +706,25 @@ def _primitive_to_action(primitive: ActionPrimitive, state: MarketWorldState) ->
         return FulfilmentAction(ActionKind.NOOP, None, None, 0, 0.0, 0)
 
     elif at == ActionType.REQUOTE:
+        # Requote: cancel existing order and place a new one at target offset.
+        # The CANCEL_REPLACE action handles both cancel + place in a single step.
+        # This is distinct from QUOTE (place new) and CHASE (place + wait + auto-cancel).
+        if state.open_orders:
+            oo = state.open_orders[0]
+            return FulfilmentAction(
+                kind=ActionKind.CANCEL_REPLACE, side=primitive.side, order_type=OrderType.LIMIT,
+                price_ticks_from_best=primitive.offset_ticks, qty_fraction=primitive.size_fraction,
+                ttl_ms=0,  # Replaced order has no TTL (stays until next cancel/requote)
+                post_only=True,
+                cancel_order_id=oo.client_order_id,
+                metadata={"requote": True, "requote_offset": primitive.offset_ticks},
+            )
+        # No existing order — fall back to PLACE
         return FulfilmentAction(
             kind=ActionKind.PLACE, side=primitive.side, order_type=OrderType.LIMIT,
             price_ticks_from_best=primitive.offset_ticks, qty_fraction=primitive.size_fraction,
-            ttl_ms=int(primitive.duration_s * 1000), post_only=True,
+            ttl_ms=0, post_only=True,
+            metadata={"requote": True, "requote_offset": primitive.offset_ticks, "fallback": True},
         )
 
     elif at == ActionType.CHASE: