Show the gateway's version when connected remotely #453

When the app is connected to a gateway (the desktop app as a client with F1.39, or a browser on the gateway), the gateway's version is hard to find. Today it shows only:

• in Settings › Connection, after Test (Test the gateway connection and API key before saving, with a version check #419);
• in Help › About › Components, in the gateway's component list (F1.34), for the operator only.

Nothing else says which version the gateway runs (maintainer request, 2026-10-27).

Wanted

• Help › About: under the app's own version, a line for the gateway, such as Gateway 0.8.0-alpha.2 (Linux service). Say how it's installed (Linux service, container, or run by hand) when the gateway reports it.
• The connection status: the gateway's version in the gateway connection's tooltip or status line.
• Different versions: when the app's and the gateway's major.minor differ, flag it next to the version. Use the same wording as Test the gateway connection and API key before saving, with a version check #419's "Versions differ" warning.
• Viewers: decide whether a viewer who isn't the operator sees the version. Proposed: yes for the version, since /auth/test already gives it without a key. Only the component list stays operator-only.

Notes

• The gateway already reports its build version: Auth.cs has Version (Test the gateway connection and API key before saving, with a version check #419), and GetComponentsAsync has the full component list.
• Restart and Update and restart from the app with the API key already exist for the Linux service gateway (F1.40, F1.40 Update and restart the Linux service gateway from the admin web app #407). This issue only covers seeing the version.