Face grouping & merging without account

[CerebralDatabank]

I like how even when used purely as a gallery app, Ente Photos on Android has on-device ML to do face recognition/grouping on local photos. However, the app does not let you name faces or merge separate faces of the same person unless you are signed in.

It doesn't make sense to restrict this behind an account; this should be possible locally.

Related:

• Offline Gallery in Linux #10126
  Also asks for face recognition without sign-in, but on Linux
• Migration from self-hosted to hosted #8557
  Discusses having the ML results be exportable