Add packed CLI end-to-end test

[itsflaid]

Summary

• add a cross-platform packed CLI E2E harness
• install the tarball into isolated Next.js and Express fixture projects
• verify version, help, analyze, snapshot, ask fallback, and doctor
• run the E2E flow in the package CI job
• record successful external Groq tarball verification without storing secrets

Verification

• pnpm test:package-e2e
• pnpm test:cli (43/43)
• pnpm build:cli
• git diff --check

[itsflaid]

yare2 error