Refactor and clean up codebase

- Removed unused constants and type aliases in app_spi_command_defs.h and temp_sensor.h.
- Simplified ISpiCommandHandler destructor to default.
- Eliminated redundant methods and comments in temp_sensor and usart0 files.
- Consolidated writeU32Le function to app_spi_command_defs.h for reuse.
- Updated comments for clarity and accuracy in task_manager.h and task_runner.cpp.
- Removed hardfault.h as it contained no declarations.
- Cleaned up CANFD and watchdog implementations by removing dead code and unnecessary comments.
- Updated version numbers in config.h to reflect recent changes.
- Enhanced error handling and diagnostics in hardfault handling.

GD32E508_DCU_APP/comm/esc_exmc_bus.cpp

@@ -60,7 +60,7 @@ void EscExmcBus::init()
     norsram_init.asyn_wait     = DISABLE;
     norsram_init.nwait_polarity = EXMC_NWAIT_POLARITY_LOW;
     norsram_init.databus_width = EXMC_NOR_DATABUS_WIDTH_16B;
-    /* 时序:按 LAN9252 HBI 要求配置 read/write wait state
+    /* TODO(spec): 时序:按 LAN9252 HBI 要求配置 read/write wait state
      * LAN9252 HBI 最小 read/write cycle = 100ns。
      * AHB=180MHz(RCU_MODIFY_UP 强制 /1)，1 HCLK = 5.6ns。
      * 6 HCLK = 33ns → 不满足，需 ≥ 18 HCLK 才能达到 100ns。
@@ -71,7 +71,9 @@ void EscExmcBus::init()
     exmc_norsram_init(&norsram_init);
     exmc_norsram_enable(CONFIG_ESC_EXMC_BANK_NOR_SRAM_REGION1);
 #else
-    /* EXMC 外设库未安装:仅占位,启用 EtherCAT 时需先安装 EXMC 组件。 */
+    /* EXMC 外设库未安装(gd32e50x_exmc.h 缺失):EtherCAT ESC EXMC 总线初始化为空,
+     * 运行期 selfTest 必失败,EtherCAT 自动禁用。启用 ESC 需先安装 EXMC 组件。 */
+#warning "EXMC peripheral library not included; EtherCAT ESC EXMC bus init is a no-op"
 #endif
 }