feat(daplink_bridge): Add firmware version query command.

[nedseb]

Description

Add a command to query the DAPLink firmware version from the STM32F103 via I2C. This allows the MicroPython driver to detect which firmware features are available (e.g. config zone commands require a specific firmware version).

Note: this issue originally targeted daplink_flash. Since then, the bridge layer has been factored out and all "bridge-level" DAPLink commands (WHO_AM_I, config zone, …) live in daplink_bridge. The version query belongs there too.

Proposed approach

Firmware side (steamicc/DAPLink)

Add a new I2C command FIRMWARE_VERSION (0x02) that returns the version as 3 bytes:

Command	Code	Parameters	Response	Description
Firmware version	0x02	NONE	3 bytes	Returns major, minor, patch as 3 bytes

The version is defined as a constant in the firmware and incremented with each release. 0x01 is already taken by WHO_AM_I, 0x02 is currently free (see lib/daplink_bridge/daplink_bridge/const.py).

MicroPython side

Add a firmware_version() method to DaplinkBridge:

def firmware_version(self):
    """Return the DAPLink firmware version as a (major, minor, patch) tuple."""
    data = self._read_reg(CMD_FIRMWARE_VERSION, 3)
    return (data[0], data[1], data[2])

Add the matching constant to daplink_bridge/const.py:

CMD_FIRMWARE_VERSION = const(0x02)

Use cases

• Skip hardware tests that require config zone if firmware is too old
• Display firmware version in diagnostic scripts
• Warn users when a firmware update is needed

Related

• steami: Add config zone in F103 internal flash gap. DAPLink#2 — Config zone implementation