On a fresh install (no integration settings yet), prompt once for the
Thingiverse/MakerWorld/Printables tokens and FlareSolverr URL, with a
"skip for now" option. /api/config exposes setupComplete (true if any
setting is configured or setup was dismissed); POST /api/setup/complete
records dismissal. DB password stays a deploy-time env var by necessity.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>