The three custom http.Transport instances built by the CLI
(`internal/transport/client.go` MCP transport, `internal/apiclient/client.go`
DingTalk OpenAPI client, `internal/app/legacy.go` IPv4-forcing registry
client) all set DialContext / TLSClientConfig / timeouts but omit the Proxy
field. Per Go's net/http contract, a non-nil Transport without an explicit
Proxy means "no proxy" — env vars are silently ignored, breaking sandboxed
or air-gapped deployments that route outbound through HTTP_PROXY /
HTTPS_PROXY.
Set Proxy: http.ProxyFromEnvironment on all three. Adds a regression test
per package that pointer-compares the Transport's Proxy func against
http.ProxyFromEnvironment (avoids flakiness from Go's envProxyOnce
memoisation when running alongside tests that read proxy env early).
修雨