1.2.1

1.2.1 — never report a mobile vault as local-only

Found on a real iPhone: 1.2.0's new setup popup fired on iOS telling a
perfectly healthy iCloud vault to move itself into iCloud.

classifyVaultLocation's branches all key off markers that only appear in a
desktop path — Mobile Documents, iCloud~md~obsidian, /Users/. Obsidian on iOS
reports a sandbox path carrying none of them, so it fell through to the
catch-all local-only verdict. Before 1.2.0 that misread was buried in the
panel; adding a popup turned it into an interruption telling the user to
break a working setup.

Falling through now means "could not tell", not "local", on any mobile
platform. Apple and Android both return their unverifiable result instead,
which shouldWarnAboutLocation already declines to warn about. Desktop paths
are still trustworthy and keep the local-only verdict.

Verified on the device: popup gone, and the phone's beacon reports 1.2.1.

137 tests, 33/33 mutations, including one per platform that removes the
guard and reproduces the false local-only.