feat(combat): expose per-pair movement and threat info in observation

src/pf1e_simulator/combat.py

@@ -678,6 +678,16 @@ class CombatEngine:
         )
         charge = self.can_charge(state, target)
         can_charge = charge is not None and charge.weapon is not None
+        occupied = state.occupied_cells()
+        target_threatens_me = bool(
+            target.active
+            and any(w.kind == "melee" for w in target.usable_attacks())
+            and self.threatened_squares(target) & occupied
+        )
+        threatening_enemies: set[str] = set()
+        for cell in occupied:
+            for enemy in self.enemies_threatening(state, cell):
+                threatening_enemies.add(enemy.combatant.id)
         return {
             "target_index": self._states.index(target),
             "distance_ft": distance_ft,
@@ -689,6 +699,9 @@ class CombatEngine:
                 self._grid, state.occupied_cells(), target.occupied_cells()
             ),
             "flanking": self._flanking_bonus(state, target) > 0,
+            "movement_cost_ft": self.movement_cost_ft(state, target),
+            "target_threatens_me": target_threatens_me,
+            "enemies_threatening_me": len(threatening_enemies),
         }
 
     def _take_turn(self, state: CombatantState) -> bool: