fix: OAuth cross-origin state loss and missing handle after callback
Two issues:
- client metadata used wisp.place domain but users access via custom
domain, causing OAuth state stored on one origin to be inaccessible
on the redirect origin
- after OAuth callback, the view page had no handle/did param, showing
"no identity specified" — now saves and restores the original URL
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>