Add test for set_effect with const char* literal

Ensures the const char* overload resolves the ambiguous call
reported in #14728.

esphome/components/addressable_light/addressable_light_display.h

@@ -33,7 +33,7 @@ class AddressableLightDisplay : public display::DisplayBuffer {
         // - Save the current effect index.
         this->last_effect_index_ = light_state_->get_current_effect_index();
         // - Disable any current effect.
-        light_state_->make_call().set_effect(0).perform();
+        light_state_->make_call().set_effect(uint32_t{0}).perform();
       }
     }
     enabled_ = enabled;

esphome/components/light/light_call.cpp

@@ -506,7 +506,7 @@ color_mode_bitmask_t LightCall::get_suitable_color_modes_mask_() {
 
 LightCall &LightCall::set_effect(const char *effect, size_t len) {
   if (len == 4 && strncasecmp(effect, "none", 4) == 0) {
-    this->set_effect(0);
+    this->set_effect(uint32_t{0});
     return *this;
   }
 

tests/components/light/common.yaml

@@ -60,6 +60,12 @@ esphome:
             }
           }
 
+      # Test set_effect with const char* doesn't cause ambiguous overload (issue #14728)
+      - lambda: |-
+          auto call = id(test_monochromatic_light).turn_on();
+          call.set_effect("None");
+          call.perform();
+
       - light.toggle: test_binary_light
       - light.turn_off: test_rgb_light
       - light.turn_on: