Release cleanup

[ada-x64]

• Stage release in build step
• Build and stage to sane output locations
• Removes orphaned ramfs item not present in default branch release

Closes #741

[Copilot]

Pull request overview

This PR restructures the Nanvix CPython release pipeline so that release artifacts are staged during the build step, and the release command only packages/validates already-built outputs (addressing Issue #741: “Do not build in def release()”).

Changes:

• Move release staging work (lxml runtime staging, sysroot/buildroot staging, ramfs image generation) into ./z build.
• Refactor packaging code to use stable staging directories (release_dir/sysroot-pkg and release_dir/buildroot-pkg) and tar them verbatim.
• Extend sysroot trimming to also remove the python<version> binary from bin/.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
.nanvix/z.py	Updates build() to perform release staging/ramfs generation; keeps release() focused on packaging/verification only.
.nanvix/package.py	Splits staging vs. tarball creation; introduces explicit staging directory helpers and verbatim tar logic.
.nanvix/config.py	Adds python<version> to sysroot bin trimming patterns.
.nanvix/build.py	Changes release install DESTDIR to release_dir/sysroot-pkg to match the new staging layout.

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.