build: prepare for publish on crates.io

[chyyuu]

Description

Implementation

Additional Context

[Copilot]

Pull request overview

This PR prepares starry-kernel and starryos for publication to crates.io by bumping their versions (to 0.2.0-preview.1 and 0.3.0-preview.2 respectively), adding required description fields, and pinning previously wildcard ("*") dependency versions. It also adds a new xtask automation tool for building, running, and testing across architectures, along with a comprehensive scripts/test.sh CI script.

Changes:

• Version and metadata updates: starry-kernel and starryos get independent explicit versions, description fields, and pinned dependency versions (gimli, page_table_multiarch) needed for crates.io publishing.
• New xtask tool: A Rust-based CLI (xtask/src/main.rs) powered by clap is added as a [[bin]] target in the root package, providing rootfs, build, run, test, and publish subcommands.
• New scripts/test.sh: A five-step Bash test script wrapping the xtask tool to check tools, run format checks, per-arch builds and QEMU boot tests, and publish dry-runs.

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
kernel/Cargo.toml	Pins version to 0.2.0-preview.1, adds description, replaces "*" dep versions with explicit ones (gimli, page_table_multiarch)
Cargo.toml	Bumps starryos to 0.3.0-preview.2, adds description, adds xtask feature, defines two [[bin]] targets, adds optional clap dependency
xtask/src/main.rs	New file: clap-based multi-arch CLI tool implementing rootfs, build, run, test, and publish subcommands
scripts/test.sh	New file: Five-step CI script delegating to cargo xtask for per-architecture build, boot, and publish testing
make/build.mk	Fixes rust_package extraction by piping through head -1 to avoid multi-match issues
Cargo.lock	Reflects dependency version changes: gimli downgraded from 0.33.0 to 0.32.3, starry-kernel and starryos version bumps, clap added

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