hardware: cache GPIO mount paths on load to avoid blocking stat

[agners]

Proposed change

Building the app container mount list called Path.exists() on candidate GPIO sysfs paths (/sys/class/gpio, /sys/devices/platform/soc) from inside DockerApp.mounts, which is invoked on the event loop. With blockbuster enabled (ha su options --detect-blocking-io on) starting the Advanced SSH & Web Terminal add-on raised BlockingError: Blocking call to os.stat, e.g.:

File "/usr/src/supervisor/supervisor/docker/app.py", line 478, in mounts
    if not Path(gpio_path).exists():
...
blockbuster.blockbuster.BlockingError: Blocking call to os.stat

Whether these sysfs paths exist is determined by the kernel at boot and does not change at runtime. Resolve them once in a new HwHelper.load() (invoked from HardwareManager.load()) and expose the result via helper.gpio_mount_paths. DockerApp.mounts stays a plain sync property and just iterates the cached tuple.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (which adds functionality to the supervisor)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request:
• Link to cli pull request:
• Link to client library pull request:

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• The code has been formatted using Ruff (ruff format supervisor tests)
• Tests have been added to verify that the new code works.

If API endpoints or add-on configuration are added/changed:

• Documentation added/updated for developers.home-assistant.io
• CLI updated (if necessary)
• Client library updated (if necessary)

[agners]

Fixes the following Blockbuster exception:

2026-05-20 13:15:02.703 ERROR (MainThread) [supervisor.jobs] Unhandled exception: Blocking call to os.stat
Traceback (most recent call last):
  File "/usr/src/supervisor/supervisor/jobs/decorator.py", line 299, in wrapper
    return await method(obj, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/src/supervisor/supervisor/docker/app.py", line 599, in run
    mounts=self.mounts,
           ^^^^^^^^^^^
  File "/usr/src/supervisor/supervisor/docker/app.py", line 478, in mounts
    if not Path(gpio_path).exists():
           ~~~~~~~~~~~~~~~~~~~~~~^^
  File "/usr/local/lib/python3.14/pathlib/__init__.py", line 671, in exists
    return os.path.exists(self)
           ~~~~~~~~~~~~~~^^^^^^
  File "<frozen genericpath>", line 19, in exists
  File "/usr/local/lib/python3.14/site-packages/blockbuster/blockbuster.py", line 109, in wrapper
    raise BlockingError(func_name)
blockbuster.blockbuster.BlockingError: Blocking call to os.stat