v2.29.0

This is a major Buildroot update. It should be seamless for most users.

• Updated dependencies
  • nerves_system_br 1.33.0
    • Buildroot 2025.11
    • Erlang/OTP 28.3
    • fwup 1.15.0
    • erlinit 1.15.1
    • nerves_heart 2.5.0
    • boardid 1.15.0