feat(board): add Hannah60B to board

[mechlovin]

Board/Shield Check-list

• This board/shield is tested working on real hardware
• Definitions follow the general style of other shields/boards upstream (Reference)
• .zmk.yml metadata file added
• Proper Copyright + License headers added to applicable files (Generally, we stick to "The ZMK Contributors" for copyrights to help avoid churn when files get edited)
• General consistent formatting of DeviceTree files
• Keymaps do not use deprecated key defines (Check using the upgrader tool)
• &pro_micro used in favor of &pro_micro_d/a if applicable
• If split, no name added for the right/peripheral half
• Kconfig.defconfig file correctly wraps all configuration in conditional on the shield symbol
• .conf file has optional extra features commented out
• Keyboard/PCB is part of a shipped group buy or is generally available in stock to purchase (OSH/personal projects without general availability should create a zmk-config repo instead)

[petejohanson]

The PR seems good to me, code wise, but I didn't actually find this for sale at the URL in the metadata.

Is this available soon? Going to be in GB or stocked?

We tend to avoid merging small runs, one offs, etc favoring separate ZMK config repos for that case.