Fix lantern glow rendering and add NPC combat animations

Disable depth testing for additive/mod blend mode batches so glow quads
render as proper light halos instead of visible transparent discs. Add
NPC swing callback to play attack animation (anim 16) when NPCs melee
in single-player combat.

src/game/game_handler.cpp

@@ -3747,6 +3747,10 @@ void GameHandler::performNpcSwing(uint64_t guid) {
     if (!entity || entity->getType() != ObjectType::UNIT) return;
     auto unit = std::static_pointer_cast<Unit>(entity);
 
+    if (npcSwingCallback_) {
+        npcSwingCallback_(guid);
+    }
+
     static std::mt19937 rng(std::random_device{}());
     std::uniform_real_distribution<float> roll(0.0f, 1.0f);