[binary_sensor] Move send_state_internal and invalidate_state to .cpp

set_new_state is a template method (~189 bytes when instantiated).
Inlining callers like send_state_internal and invalidate_state causes
the template code to be duplicated at every call site (publish_state,
Filter::output, BinarySensorInvalidateAction::play, etc.), adding
~384 bytes of flash.

Keep these as out-of-line definitions in the .cpp so the template
is instantiated once.

esphome/components/binary_sensor/binary_sensor.cpp

@@ -32,6 +32,10 @@ void BinarySensor::publish_initial_state(bool new_state) {
   this->invalidate_state();
   this->publish_state(new_state);
 }
+// Defined out-of-line to prevent set_new_state template from being inlined at each call site,
+// which would duplicate ~189 bytes of template code per caller (publish_state, Filter::output, etc.)
+void BinarySensor::send_state_internal(bool new_state) { this->set_new_state(new_state); }
+void BinarySensor::invalidate_state() { this->set_new_state({}); }
 
 void BinarySensor::on_state_changed_(const optional<bool> &old_state, const optional<bool> &new_state, bool had_state) {
   StatefulEntityBase::on_state_changed_(old_state, new_state, had_state);

esphome/components/binary_sensor/binary_sensor.h

@@ -57,7 +57,8 @@ class BinarySensor : public StatefulEntityBase<bool> {
 
   // ========== INTERNAL METHODS ==========
   // (In most use cases you won't need these)
-  void send_state_internal(bool new_state) { this->set_new_state(new_state); }
+  /// Defined in .cpp to avoid inlining set_new_state template code at every call site.
+  void send_state_internal(bool new_state);
 
   /// Return whether this binary sensor has outputted a state.
   virtual bool is_status_binary_sensor() const;

esphome/core/entity_base.h

@@ -320,7 +320,8 @@ template<typename T> class StatefulEntityBase : public EntityBase {
   /// Return the current state if available, otherwise return the provided default.
   T get_state_default(T default_value) const { return this->has_state() ? this->get_state() : default_value; }
   /// Clear the state — sets has_state() to false and fires callbacks with nullopt.
-  void invalidate_state() { this->set_new_state({}); }
+  /// Defined out-of-line in subclass .cpp to avoid inlining set_new_state template code at every call site.
+  void invalidate_state();
 
   template<typename F> void add_full_state_callback(F &&callback) {
     this->full_state_callbacks_.add(std::forward<F>(callback));