fix(skills): use VIP Membership for paid installs

[MarkShawn2020]

Summary

• Replace removed per-Skill price/purchase calls with the current VIP Membership entitlement check and gated download.
• Bind membership responses to the requested Skill; preserve legacy owners, account refresh and free installs.
• Guide non-owners to /vip without a per-Skill charge.
• Bump npm package to 0.5.1.

Validation

• 52 tests: 51 passed, 0 failed, 1 original platform skip.
• 10 HTTP fixtures cover VIP, existing owner, guest, expired session, 401/403, wrong/missing Skill name, and free install. No old price/purchase requests.
• Syntax, help, diff and package dry-run passed.
• Same fixtures run on baseline, modified and restored separate copies; portable rollback and patch reconstruction verified.
• Focused independent review closed the response-name binding finding.

Publication

Use the existing Trusted Publisher CI workflow after normal test checks; then verify a real VIP project-local installation of 3d-motion-media-creator.