A fresh install had no prompt for general.public_base_url, so first-run agent
installs/share links silently used the request Host header. Add a "Steward URL"
field to the first-run /setup page (create-admin), pre-filled with the current
address, with help text. setup_post saves general.public_base_url and applies
it to app.config immediately (no restart). Editable later in Settings → General.
Scribe #896.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
bvandeusen
f80f6c87e8