Treat phone-number-already-exists messages on the signup password page as the same restartable step-3 failure path used for phone/password mismatches.
Also adds a regression test covering the Chinese phone-exists error so the flow stops immediately instead of retrying the password submit loop.
- merge the latest dev branch into PR #130 before applying local fixes
- detect visible split OTP inputs even when the page exposes numeric single-character fields
- stop assuming verification success after repeated auth retry-page recovery failures
QLHazyCoder