test(ci): enable network feature in integration tests after first release

[CalvinAllen]

Summary

The integration tests currently build without the network feature because no releases exist yet. Once the first release is published, we should update the integration tests to use the full network feature to verify real binary downloads work.

Changes needed

Update .github/workflows/integration-test.yml:

- run: cargo build --release --no-default-features --features parallel
+ run: cargo build --release

Context

PR #40 added real binary download functionality to init and upgrade commands. The tests temporarily use placeholder binaries until releases are available.