STM32WB55 Support and Reliable Cross-Family DFU Implementation

Description

Major update introducing STM32WB55 support and a complete overhaul of software DFU entry across supported STM32 families.

Added

• STM32WB55 support (tested on WeAct STM32WB55CGU6)
• Support via P-NUCLEO-WB55 and NUCLEO WB55 USB Dongle board definitions
• Nucleo-64 board definition support (F1/F4/G4 variants should work)
• dfu_boot_stm32wb.c for reliable WB55 DFU entry
• Additional hardware validation: WeAct STM32G474 and STM32F405

Changed

• DFU implementation rewritten for reliability:
  • F1/F4/G4 use direct ROM bootloader jump
  • WB55 uses magic value in BKP0R + NVIC_SystemReset() with early Reset_Handler interception
• boards.txt now requires extra lines to enable 1200bps touch
• Updated boards_txt_additions.txt with new format and Nucleo_64 entry

Known Limitations

• Generic WB55 board definitions lack proper USB clock configuration and are not supported. Use P-NUCLEO-WB55 or NUCLEO WB55 USB Dongle board definitions.
• STM32F1 DFU entry requires further validation on boards with factory bootloader.

This release significantly improves stability and expands supported hardware.