fix(ci): restore AS checks and stabilize gateway build

[jialez0]

Summary

• initialize the challenge key rotation test config through Config::default so new optional AS fields do not break the integration test
• add policy-to-Artifact-Server tests for the request wire shape, resolved/denied results, and infrastructure error propagation
• exercise no-default and isolated policy-artifact-server feature builds in Rust CI
• make the Gateway GOPROXY configurable and use proxy.golang.org in GitHub Actions while retaining the existing Aliyun default for local builds

Root cause

After PR #220 was merged, the main branch exposed two failures: challenge_key_rotation.rs no longer initialized every Config field, and the Aliyun Go proxy repeatedly returned invalid module zip files to the GitHub runner.

Validation

• cargo +1.76 test -p attestation-service -p verifier
• cargo +1.76 test -p attestation-service --lib --no-default-features
• cargo +1.76 test -p attestation-service --lib --no-default-features --features policy-artifact-server
• cargo +1.76 test -p attestation-service --lib --no-default-features --features policy-rvps
• cargo +1.76.0 clippy -p attestation-service -p verifier -- -D warnings -A clippy::derive_partial_eq_without_eq
• cargo +1.76 fmt -p attestation-service -p verifier --check
• go test ./... under trustee-gateway
• actionlint .github/workflows/docker-build.yml .github/workflows/rust-check.yml

[ostest-bot]

@jialez0 ，您好，您的请求已接收，请耐心等待结果。

[ostest-bot]

@jialez0 ，您好，未检测到有镜像需要构建，如需重新检测请评论 /start 。