feat(canfd): 添加直接发送CANFD帧功能用于SPI桥接场景

- 新增 CanFd::transmitFrame() 方法，支持绕过软件队列直接调用
  硬件发送CANFD扩展帧
- 实现参数验证，包括通道索引、数据指针和DLC长度检查
- 集成GD32E508特定的FD标志和波特率切换设置
- 更新诊断统计信息，记录发送计数、最后ID、通道和负载长度

feat(spi-command): 添加SPI到CAN总线桥接发送命令类型

- 引入 kTypeCanSend (0xC0) 命令类型用于SPI-CAN桥接
- 实现CAN_SEND命令处理逻辑，解析载荷中的通道、ID和数据
- 支持3个CAN通道(0/1/2)，验证通道有效性防止越界访问
- 添加详细的错误处理和日志记录机制

refactor(config): 更新SPI命令ACK确认码和构建版本号

- 将CONFIG_SPI_APP_OTA_BOOT_ACK_OK从0xA5U改为0xB5U以避免冲突
- 提升APP_FW_VERSION_BUILD从1到2以反映新功能集成

GD32E508_DCU_APP/device/app_spi_command.cpp

@@ -12,6 +12,7 @@
  */
 
 #include "device/app_spi_command.h"
+#include "device/canfd.h"
 
 extern "C" {
 #include "gd32e50x_exti.h"
@@ -34,6 +35,7 @@ extern "C" {
  * ============================================================ */
 static constexpr uint8_t kSof = 0xA5U;
 static constexpr uint8_t kTypeBootReq   = 0xB0U;
+static constexpr uint8_t kTypeCanSend   = 0xC0U;
 static constexpr uint8_t kTypeOtaReq    = 0x01U;
 static constexpr uint8_t kTypeAppPing   = 0xA1U;
 static constexpr uint8_t kTypeOtaData   = 0x02U;
@@ -359,6 +361,47 @@ void AppSpiCommand::processCommand()
                 spi_build_frame(kRspError, &err, 1U, s_txBuf, &tx_len);
             }
             break;
+
+        case kTypeCanSend:
+            /* SPI→CAN 桥接：解析载荷并通过 CanFd 直接发送到 CAN 总线
+             *
+             * payload 布局 (6~69B):
+             * [0]    = channel (0/1/2)
+             * [1..4] = ext_id  (32-bit Big-Endian)
+             * [5..]  = CAN data (1~64 bytes, 实际长度 = payload_len - 5)
+             */
+            if (payload_len < 6U) {
+                /* 载荷太短：至少需要 1B channel + 4B ext_id + 1B data */
+                logDeferred("[SPI-APP] CAN_SEND 载荷太短 → ERROR");
+                uint8_t err = 0xE0U;
+                spi_build_frame(kRspError, &err, 1U, s_txBuf, &tx_len);
+            } else {
+                uint8_t  can_ch   = payload[0];
+                uint32_t can_id   = (static_cast<uint32_t>(payload[1]) << 24)
+                                  | (static_cast<uint32_t>(payload[2]) << 16)
+                                  | (static_cast<uint32_t>(payload[3]) << 8)
+                                  |  static_cast<uint32_t>(payload[4]);
+                const uint8_t *can_data = &payload[5];
+                uint8_t  can_dlc  = static_cast<uint8_t>(payload_len - 5U);
+
+                if (can_ch >= 3U) {
+                    logDeferredFmt("[SPI-APP] CAN_SEND 通道非法: CH%d → ERROR", can_ch);
+                    uint8_t err = 0xE1U;
+                    spi_build_frame(kRspError, &err, 1U, s_txBuf, &tx_len);
+                } else {
+                    bool ok = CanFd::transmitFrame(can_ch, can_id, can_data, can_dlc);
+                    if (ok) {
+                        logDeferredFmt("[SPI-APP] CAN_SEND CH%d → OK", can_ch);
+                        uint8_t ack = 0x00U;  /* 成功 */
+                        spi_build_frame(kRspAck, &ack, 1U, s_txBuf, &tx_len);
+                    } else {
+                        logDeferredFmt("[SPI-APP] CAN_SEND CH%d FIFO满 → ERROR", can_ch);
+                        uint8_t err = 0xE2U;  /* FIFO 满 */
+                        spi_build_frame(kRspError, &err, 1U, s_txBuf, &tx_len);
+                    }
+                }
+            }
+            break;
         }
         s_txLen = (uint8_t)tx_len;
         s_txPos = 0U;