Fix DB host: use 172.17.0.1 (Docker bridge gateway to host)

Supabase DB is on a compose-internal network not reachable via
CapRover service names. Docker bridge gateway routes to host where
port 5432 is bound. Also make migration non-fatal so server starts
regardless.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>