pgsqlCopyFromArray can block the drain worker forever on certain libpq
failures (mid-stream network stall, broken SSL renegotiation) — it never
returns false, it just hangs. Wrap it with the same SIGALRM backstop
already used in connect(): worker exits after 60s so the parent SIGCHLD
handler restarts it.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>