Extract the shared RequestAuthInfo -> Open -> WaitToken sequence from the
login flow and the SSH JWT flow into runOAuthFlow. Open is now called
synchronously by both flows, matching iOS; openers must post their UI
work instead of blocking, which the app-side openers already do.
The SSH flow read its login hint via profilemanager.GetLoginHint, which
resolves desktop-layout files that the Android app never writes, so the
hint was always empty and the device-code flow could prompt for account
selection. Both flows now read the hint from the profile account file
via the config path, taken from authSnapshot so a concurrent profile
switch cannot pair one profile's config with another's hint.