feat(ch390): optimize SPI transfer, MAC fallback, and build settings for V1.0.0

- increase UART DMA/ring buffer sizes for mux traffic
- switch SPI1 to Mode0 with prescaler /2 and align CubeMX settings
- refactor CH390 memory read/write path with chunked SPI read and HAL bulk write
- fallback to hardware MAC when configured MAC is invalid (all-zero)
- add mux frame RTT logs and remove redundant UART1 polling
- update Keil post-build viewer integration and include build viewer artifacts
- update AT manual with all-zero MAC behavior

App/uart_trans.h

@@ -26,10 +26,10 @@ typedef struct {
     uint8_t payload[256];
 } uart_mux_frame_t;
 
-#define UART_RX_DMA_BUFFER_SIZE   128u
-#define UART_TX_DMA_BUFFER_SIZE   128u
-#define UART_RX_RING_BUFFER_SIZE  256u
-#define UART_TX_RING_BUFFER_SIZE  256u
+#define UART_RX_DMA_BUFFER_SIZE   256u
+#define UART_TX_DMA_BUFFER_SIZE   256u
+#define UART_RX_RING_BUFFER_SIZE  512u
+#define UART_TX_RING_BUFFER_SIZE  384u
 #define UART_DEFAULT_BAUDRATE     115200u
 
 typedef struct {