Add Hardware settings doc page (#2518)
* Add Hardware settings doc page
Document the dedicated Hardware settings page: how to register the GPUs,
CPUs and Apple Silicon you own, and how that drives model compatibility
estimates, the profile TFLOPS badge, and the community hardware page.
Adds docs/hub/hardware.md and registers it in the Models nav next to
Local Apps.
* Put Hardware before Local Apps in the nav
* Address review: hardware is public by default, wording tweaks
- Fix the visibility default: hardware is public by default; turn off
Publicly Visible to keep it private (per review).
- Reframe the intro so profile sharing and the privacy control are clear.
- Minor wording: 'get up and running', 'estimated total compute power'.
* Add Hardware settings screenshot (light/dark)
