Add USART2 support and modify system clock configuration

- Implemented USART2 initialization and interrupt handling.
- Added a function to send data to the server via USART2.
- Updated the main application to utilize USART2 for communication.
- Changed system clock configuration to use HSE and PLL for higher frequency.
- Adjusted SPI1 baud rate prescaler for improved performance.
- Enhanced LED control logic based on RFID card detection.
- Updated project configuration to reflect new USART2 settings.

Core/Src/stm32f1xx_it.c

@@ -57,6 +57,7 @@
 /* External variables --------------------------------------------------------*/
 extern I2C_HandleTypeDef hi2c1;
 extern UART_HandleTypeDef huart1;
+extern UART_HandleTypeDef huart2;
 /* USER CODE BEGIN EV */
 
 /* USER CODE END EV */
@@ -227,6 +228,20 @@ void USART1_IRQHandler(void)
   /* USER CODE END USART1_IRQn 1 */
 }
 
+/**
+  * @brief This function handles USART2 global interrupt.
+  */
+void USART2_IRQHandler(void)
+{
+  /* USER CODE BEGIN USART2_IRQn 0 */
+
+  /* USER CODE END USART2_IRQn 0 */
+  HAL_UART_IRQHandler(&huart2);
+  /* USER CODE BEGIN USART2_IRQn 1 */
+
+  /* USER CODE END USART2_IRQn 1 */
+}
+
 /* USER CODE BEGIN 1 */
 
 /* USER CODE END 1 */