fix(network): 恢复 worker 默认路由指向 gateway 容器，修复 DNS 不通 #50

Job	Run time
verify / Web Build	14s
verify / Image Size Regression (BASE-04 ≤ 2GB)	1m 18s
verify / Go Tests	1m 6s
verify / Performance Benchmark (synthetic 10k, local baseline)	1m 13s
create-release	12s
build-binaries (linux, amd64)	33s
build-binaries (linux, arm64)	33s
build-binaries (darwin, amd64)	35s
build-binaries (darwin, arm64)	32s
publish-images / build (control-plane, deploy/docker/control-plane/Dockerfile, .)	7m 48s
publish-images / build (sing-box-gateway, deploy/docker/sing-box-gateway/Dockerfile, .)	36s
publish-images / build (managed-user, deploy/docker/managed-user/Dockerfile, .)	1m 56s
publish-images / build (admin, deploy/docker/admin/Dockerfile, .)	4m 1s
update-homebrew	8s
	20m 45s

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