Docker named volumes and host bind-mounts may be owned by root,
causing "open data/model_pricing.sha256: permission denied" when
the container runs as the non-root sub2api user.
Add an entrypoint script that fixes /app/data ownership before
dropping to sub2api via su-exec. Replace USER directive with the
entrypoint approach across all three Dockerfiles and update both
GoReleaser configs to include the script in Docker build contexts.
GO-2026-4602 (os), GO-2026-4601 (net/url), GO-2026-4600 and
GO-2026-4599 (crypto/x509). The crypto/x509 fixes are only
available in go1.26.1+, not backported to go1.25.x.
