fixes setup wizard bugs reported by community:
- runtime crash from
localkeyword used outside a function - SSH mismatch: stop pairing wrong SSH key with wrong username when auto-constructing mirror URL
- blank personal username now confirms SSH-detected account instead of silently using it
- new HTTPS fallback: when SSH push fails on mirror (work-only laptop), offers to switch remote to HTTPS + PAT
- restores original SSH remote if HTTPS auth fails (no partial state)
- centralized push testing, owner verification, and URL validation helpers