fix(scenario): action-multiunit-coordination — HoldFire agent units after engine movement fixes

The engine movement fixes made a default-stance unit auto-hunt the
nearest visible enemy, so an idle/observe-only policy self-delivered
the force across the map, destroyed the marker buildings and
triggered an enemy-elimination auto-done DRAW before the timeout fail
could bite on medium/hard. Setting the agent units to stance:0
(HoldFire) restores 'units only move when explicitly ordered': a
stall is now a real reachable timeout LOSS and the split capability
stays load-bearing. Recovers tests/test_units_in_region.py.

openra_bench/scenarios/packs/action-multiunit-coordination.yaml

@@ -36,9 +36,19 @@ base:
   termination: {max_ticks: 8000}
   actors:
     # Two agent groups in the spawn corner (x < 25) that must be split
-    # and driven to separate regions at the same time.
-    - {type: 2tnk, owner: agent, position: [5, 6],  count: 3}
-    - {type: 1tnk, owner: agent, position: [7, 10], count: 3}
+    # and driven to separate regions at the same time. `stance: 0`
+    # (HoldFire) is load-bearing: after the engine movement fixes a
+    # default-stance unit auto-HUNTS the nearest visible enemy
+    # (stance:3 AttackAnything path), so an idle/observe-only policy
+    # would self-deliver the force across the map, destroy the
+    # marker buildings and trigger an enemy-elimination auto-`done`
+    # DRAW before the timeout fail can bite (and risk a
+    # laziest-play-wins inversion). HoldFire units only move when
+    # the agent explicitly orders `move_units`, so a stall is a real
+    # reachable timeout LOSS and the split capability stays
+    # load-bearing.
+    - {type: 2tnk, owner: agent, position: [5, 6],  count: 3, stance: 0}
+    - {type: 1tnk, owner: agent, position: [7, 10], count: 3, stance: 0}
     # Static enemy buildings mark the destination regions.
     - {type: fact, owner: enemy, position: [110, 6]}
     - {type: proc, owner: enemy, position: [110, 33]}
@@ -78,13 +88,17 @@ levels:
       lanes; the bottom-left route is clear.
     overrides:
       actors:
-        - {type: 2tnk, owner: agent, position: [5, 6],  count: 3}
-        - {type: 1tnk, owner: agent, position: [7, 10], count: 3}
+        # `stance: 0` (HoldFire) on every agent unit — see the base
+        # `actors` note: a default-stance unit auto-hunts after the
+        # engine movement fixes, self-delivering the force and
+        # collapsing a stall to an auto-`done` DRAW.
+        - {type: 2tnk, owner: agent, position: [5, 6],  count: 3, stance: 0}
+        - {type: 1tnk, owner: agent, position: [7, 10], count: 3, stance: 0}
         # Jeeps staged at y=24 (south of centre) so the SE-bound
         # column does NOT route past the NE picket at y=8 — at y=14
         # the fragile jeeps were attrited to death before reaching
         # the SE region, making the 3/3/2 split unsolvable.
-        - {type: jeep, owner: agent, position: [5, 24], count: 2}
+        - {type: jeep, owner: agent, position: [5, 24], count: 2, stance: 0}
         - {type: fact, owner: enemy, position: [115, 6]}    # NE corner
         - {type: proc, owner: enemy, position: [115, 34]}   # SE corner
         - {type: powr, owner: enemy, position: [20, 36]}     # bottom-left
@@ -134,13 +148,17 @@ levels:
         # the coordinate-blind agent the position feedback it needs.
         enemy_building_spotted: true
       actors:
-        - {type: 2tnk, owner: agent, position: [5, 6],  count: 3}
-        - {type: 1tnk, owner: agent, position: [7, 10], count: 3}
+        # `stance: 0` (HoldFire) on every agent unit — see the base
+        # `actors` note: a default-stance unit auto-hunts after the
+        # engine movement fixes, self-delivering the force and
+        # collapsing a stall to an auto-`done` DRAW.
+        - {type: 2tnk, owner: agent, position: [5, 6],  count: 3, stance: 0}
+        - {type: 1tnk, owner: agent, position: [7, 10], count: 3, stance: 0}
         # Jeeps staged at y=24 (south of centre) so the SE-bound
         # column does NOT route past the NE picket at y=8 — at y=14
         # the fragile jeeps were attrited to death before reaching
         # the SE region, making the 3/3/2 split unsolvable.
-        - {type: jeep, owner: agent, position: [5, 24], count: 2}
+        - {type: jeep, owner: agent, position: [5, 24], count: 2, stance: 0}
         - {type: fact, owner: enemy, position: [115, 6]}    # NE corner
         - {type: proc, owner: enemy, position: [115, 34]}   # SE corner
         - {type: powr, owner: enemy, position: [20, 36]}     # bottom-left