Youssef's review caught a residual false-positive: resolveTestWsUrl
swallowed an OAuth ticket-mint failure and returned null, so the caller
skipped the WS probe and reported the remote test as reachable. But the
real boot path (resolveRemoteBackend) treats a mint failure as a hard
'session expired' auth error and refuses to connect — so an expired OAuth
session passed the test then failed boot, the exact false-positive this
PR exists to kill.
Extract resolveTestWsUrl into the electron-free connection-config.cjs
(injectable mintTicket) so it's unit-testable, and make OAuth mint
failure throw an actionable needsOauthLogin error instead of skipping.
Adds the three cases Youssef requested plus a mintTicket-required guard.