Use walking speed for swimming actor with water walking for pathfinding

This will make them find shorter paths nearby shores.

CHANGELOG.md

@@ -121,6 +121,7 @@
     Bug #7723: Assaulting vampires and werewolves shouldn't be a crime
     Bug #7724: Guards don't help vs werewolves
     Bug #7742: Governing attribute training limit should use the modified attribute
+    Bug #7758: Water walking is not taken into account to compute path cost on the water
     Feature #2566: Handle NAM9 records for manual cell references
     Feature #3537: Shader-based water ripples
     Feature #5173: Support for NiFogProperty

apps/openmw/mwmechanics/aipackage.cpp

@@ -492,8 +492,6 @@ DetourNavigator::AreaCosts MWMechanics::AiPackage::getAreaCosts(const MWWorld::P
     const DetourNavigator::Flags flags = getNavigatorFlags(actor);
     const MWWorld::Class& actorClass = actor.getClass();
 
-    const float swimSpeed = (flags & DetourNavigator::Flag_swim) == 0 ? 0.0f : actorClass.getSwimSpeed(actor);
-
     const float walkSpeed = [&] {
         if ((flags & DetourNavigator::Flag_walk) == 0)
             return 0.0f;
@@ -502,6 +500,14 @@ DetourNavigator::AreaCosts MWMechanics::AiPackage::getAreaCosts(const MWWorld::P
         return actorClass.getRunSpeed(actor);
     }();
 
+    const float swimSpeed = [&] {
+        if ((flags & DetourNavigator::Flag_swim) == 0)
+            return 0.0f;
+        if (hasWaterWalking(actor))
+            return walkSpeed;
+        return actorClass.getSwimSpeed(actor);
+    }();
+
     const float maxSpeed = std::max(swimSpeed, walkSpeed);
 
     if (maxSpeed == 0)