[light] Fix schedule_show not enabling loop for idle addressable lights (#12302)

esphome/components/light/addressable_light.h

@@ -70,7 +70,7 @@ class AddressableLight : public LightOutput, public Component {
     this->state_parent_ = state;
   }
   void update_state(LightState *state) override;
-  void schedule_show() { this->state_parent_->next_write_ = true; }
+  void schedule_show() { this->state_parent_->schedule_write_(); }
 
 #ifdef USE_POWER_SUPPLY
   void set_power_supply(power_supply::PowerSupply *power_supply) { this->power_.set_parent(power_supply); }

esphome/components/light/light_state.cpp

@@ -305,8 +305,7 @@ void LightState::set_immediately_(const LightColorValues &target, bool set_remot
     this->remote_values = target;
   }
   this->output_->update_state(this);
-  this->next_write_ = true;
-  this->enable_loop();
+  this->schedule_write_();
 }
 
 void LightState::disable_loop_if_idle_() {

esphome/components/light/light_state.h

@@ -277,6 +277,12 @@ class LightState : public EntityBase, public Component {
   /// Disable loop if neither transformer nor effect is active
   void disable_loop_if_idle_();
 
+  /// Schedule a write to the light output and enable the loop to process it
+  void schedule_write_() {
+    this->next_write_ = true;
+    this->enable_loop();
+  }
+
   /// Store the output to allow effects to have more access.
   LightOutput *output_;
   /// The currently active transformer for this light (transition/flash).