[Java] `linuxmusl-x64`, or `linuxmusl-arm64`: Embed Rust-based Copilot CLI Runtime and cease requiring Node.js

Predecessor #2308

@roji wrote:

Java does not currently publish macOS x64 or Linux musl classifiers - but we'll add those soon enough (so better to add these now while we're at it)

Work items in this Epic address this gap.

Confirmed — the assertion is true for the current checkout (d5c9d06, September 7, 2026).

Java publishes these native classifiers:

• linux-x64 and linux-arm64 — glibc only
• win32-x64 and win32-arm64
• darwin-arm64

There is no darwin-x64, linuxmusl-x64, or linuxmusl-arm64 build/profile in java/copilot-native/pom.xml or either Java publishing workflow. The release summary explicitly lists only those five classifiers in .github/workflows/java-publish-maven.yml:625-633.

Additional confirmation:

• java/copilot-native/scripts/validate-native-host.mjs:6-20 rejects musl Linux hosts.
• java/README.md:604 explicitly identifies Intel macOS and Linux musl as unsupported.
• Although validate-native-artifact.mjs accepts macOS x64 and musl-shaped classifier names for generic artifact validation, no Maven profile or publication job produces them.