feat: add alpha version testing to all CI test jobs

[fengmk2]

Summary

• Add version: [latest, alpha] matrix dimension to all 8 test jobs in CI workflow
• Both latest and alpha versions are now tested simultaneously across all test scenarios (basic install, node-version, cache with pnpm/npm/yarn, vp exec, vp install+exec, registry-url)
• Step names include the version for easier identification in CI logs

Test plan

• CI passes for all latest version matrix entries (existing behavior)
• CI passes for all alpha version matrix entries (new coverage)

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Expands the CI workflow to validate this action against both the current stable (latest) and prerelease (alpha) Vite+ dist-tags across the existing test scenarios, improving early detection of breaking changes in upcoming releases.

Changes:

• Adds a version: [latest, alpha] matrix axis to each of the existing CI test jobs.
• Passes ${{ matrix.version }} into the action version input and includes it in step names for clearer CI logs.

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[Copilot]

Pull request overview

This PR expands CI coverage by running the action tests against both the latest and alpha Vite+ versions via a workflow matrix, improving confidence across release channels.

Changes:

• Add version: [latest, alpha] matrix dimension to the CI test jobs and pass version through to the action.
• Update setup step names to include the selected version for clearer CI logs.
• Update the Vite+ install script URLs used by the action.

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/install-viteplus.ts	Changes the remote installer script endpoints used during Vite+ installation.
.github/workflows/test.yml	Adds a version matrix to test jobs and wires matrix.version into the action steps.

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