fix(docker): set migrations dir permissions to 755 on COPY (#475)

Docker COPY preserves build-host file permissions. On hosts with a
restrictive umask (e.g. 0027), the migrations directory is copied as
750 root:root, making it unreadable by the openshell user at runtime
and causing the server to crash with a permission denied error on
startup.

Using --chmod=755 ensures the directory is always world-readable
regardless of the build host umask.

Signed-off-by: Evan Lezar <elezar@nvidia.com>

Author: elezar

deploy/docker/Dockerfile.images

@@ -168,7 +168,7 @@ WORKDIR /app
 COPY --from=gateway-builder /build/out/openshell-server /usr/local/bin/
 
 RUN mkdir -p /build/crates/openshell-server
-COPY crates/openshell-server/migrations /build/crates/openshell-server/migrations
+COPY --chmod=755 crates/openshell-server/migrations /build/crates/openshell-server/migrations
 
 USER openshell
 EXPOSE 8080