v1.2.0-beta.1: Beta: desktop port grouping, tunnel paths, and a probing compatibility switch

Beta: desktop port grouping, tunnel paths, and a probing compatibility switch

This is a beta build for testers ahead of the 1.2.0 release. Nothing about
your Pro licence or how the app works changes. Please run your usual setup
and flag anything that looks off, especially around Thunderbolt docks and
the Connected devices view.

What to test

• Desktop built-in USB ports no longer group under a Thunderbolt dock.
  On a Mac mini or Mac Studio, the machine's own front USB-C ports were being
  drawn as if they hung off a connected dock. They now show separately.
  Raised by @CronoCX in
  discussion #417.
• Connected devices tree now roots under the Thunderbolt link. For Pro
  users, the device tree shows the downstream Thunderbolt device with its
  live link speed at the top, plus tunnel-path attribution: which display or
  data tunnel each device is riding.
• New "Skip deep USB probing" compatibility switch. If deep USB probing
  ever stalls or misbehaves on your Mac, Settings now has a switch to turn it
  off. Everything else keeps working. Thanks @asapuntz (#429).

Also in this build

• Test-kit probe hardening and a correction to how hardware identifiers are
  captured.
• Internal correctness fixes to port join keys.