Playerbot: only assist targets the owner is actually fighting

ResolveOwnerAssistTarget preferred GetSelectedUnit() over the victim, so
merely targeting a neutral/yellow mob made every bot attack it. Now the
victim (real combat target) is preferred, and the selected-unit fallback
only counts when the owner is IN combat and targeting that unit (a cast
in flight) — a selected-but-unattacked mob never pulls the squad.

src/modules/PlayerbotV2/PlayerbotV2.cpp

@@ -149,7 +149,12 @@ Unit* ResolveOwnerAssistTarget(Player* owner)
     if (!owner || !owner->IsInWorld())
         return nullptr;
 
-    Unit* t = owner->GetSelectedUnit();
+    // Assist only what the owner is ACTUALLY fighting. Prefer the victim
+    // (the unit the owner is attacking); a merely-selected target (e.g. a
+    // neutral/yellow mob the player is hovering or inspecting) must NOT pull
+    // the squad into combat — bots only join once the player commits to an
+    // attack.
+    Unit* t = owner->GetVictim();
     if (t)
     {
         if (!t->IsAlive() || t->GetMap() != owner->GetMap())
@@ -160,11 +165,20 @@ Unit* ResolveOwnerAssistTarget(Player* owner)
 
     if (!t)
     {
-        t = owner->GetVictim();
-        if (t && (!t->IsAlive() || t->GetMap() != owner->GetMap()))
-            t = nullptr;
-        if (t && !owner->IsValidAttackTarget(t))
-            t = nullptr;
+        // Casters/ranged can have a selected target while the victim field
+        // lags a cast — treat the selection as an assist target only when the
+        // owner is genuinely ENGAGED with it (in combat and targeting it).
+        t = owner->GetSelectedUnit();
+        if (t)
+        {
+            if (!t->IsAlive() || t->GetMap() != owner->GetMap())
+                t = nullptr;
+            else if (!owner->IsValidAttackTarget(t))
+                t = nullptr;
+            else if (!owner->IsInCombat() ||
+                     owner->GetTarget() != t->GetGUID())
+                t = nullptr;
+        }
     }
 
     return t;