Update Aspire skill to support JS package manager-specific AppHost launchers

[maddymontaquila]

Summary

Update the general Aspire skill so agents understand and support JavaScript/TypeScript AppHosts launched through different JS package managers, not just a single assumed launcher flow.

Motivation

When working with TS/JS AppHosts, the correct launch/install command may depend on the package manager and project metadata. The skill should guide agents to detect and use the appropriate package manager, such as npm, pnpm, yarn, or bun, and avoid assuming one fixed command shape.

Proposed behavior

• Detect the package manager from lockfiles and package metadata, for example package-lock.json, pnpm-lock.yaml, yarn.lock, bun.lockb/bun.lock, or packageManager in package.json.
• Use the matching package-manager command when installing dependencies and launching the AppHost.
• Document fallback behavior when the package manager cannot be determined.
• Ensure generated or recommended commands preserve existing repo conventions and avoid changing package manager files unexpectedly.

Related skill updates

This may also need an aspireify skill reference tweak so one-time initialization of existing apps wires TS/JS AppHosts consistently with the detected package manager.

[spboyer]

@maddymontaquila @IEvangelist

Implemented in microsoft/aspire-skills#39. The PR aligns the skills with Aspire CLI package-manager resolution, preserves aspire start for lifecycle operations, rejects Yarn Classic, and adds focused eval coverage.