refactor: move Arduino demo from func_loader to Project/Application

Rename fl_port_arduino.cpp -> fl_demo.cpp and move to
Project/Application/ where other demo code lives.

Rename func_loader_run() -> fl_demo_run() to match the new role.
Update main.cpp extern declaration accordingly.

The file is a demo application, not a porting layer.

Author: FASTSHIFT

App/func_loader/fl_port_arduino.cpp Project/Application/fl_demo.cppApp/func_loader/fl_port_arduino.cpp renamed to Project/Application/fl_demo.cpp

@@ -22,8 +22,8 @@
  */
 
 /**
- * @file   func_loader_port_arduino.cpp
- * @brief  Arduino/STM32 porting layer
+ * @file   fl_demo.cpp
+ * @brief  Arduino/STM32 function loader demo application
  *
  * Supports two allocation modes (selected via CMake FL_ALLOC_MODE):
  *   - FL_ALLOC_STATIC: Static buffer allocation (default)
@@ -140,7 +140,7 @@ static void blink_led() {
     last_time = millis();
 }
 
-void func_loader_run(void) {
+void fl_demo_run(void) {
     pinMode(LED_PIN, OUTPUT);
 
     /* Initialize allocator (mode-specific) */

Project/Application/main.cpp

@@ -77,8 +77,8 @@ int main(void)
 
 #elif APP_SELECT == APP_FUNC_LOADER
     /* Function loader mode */
-    extern void func_loader_run(void);
-    func_loader_run();
+    extern void fl_demo_run(void);
+    fl_demo_run();
 
 #else
 #error "Invalid APP_SELECT value"