[core] Inline after_loop_tasks_() into header

Trivial one-liner (single assignment) called from the inlined loop()
and setup(). Eliminates another unnecessary function call.

esphome/core/application.cpp

@@ -476,11 +476,6 @@ void Application::before_loop_tasks_(uint32_t loop_start_time) {
   this->in_loop_ = true;
 }
 
-void Application::after_loop_tasks_() {
-  // Clear the in_loop_ flag to indicate we're done processing components
-  this->in_loop_ = false;
-}
-
 #ifdef USE_LWIP_FAST_SELECT
 bool Application::register_socket(struct lwip_sock *sock) {
   // It modifies monitored_sockets_ without locking — must only be called from the main loop.

esphome/core/application.h

@@ -618,7 +618,7 @@ class Application {
   void enable_pending_loops_();
   void activate_looping_component_(uint16_t index);
   void before_loop_tasks_(uint32_t loop_start_time);
-  void after_loop_tasks_();
+  inline void ESPHOME_ALWAYS_INLINE after_loop_tasks_() { this->in_loop_ = false; }
 
   /// Process dump_config output one component per loop iteration.
   /// Extracted from loop() to keep cold startup/reconnect logging out of the hot path.