Move Node.js versions to Active/Sunset/Decommissioned lifecycle

[catplat]

Summary

Ports the Node.js version-lifecycle changes from Mintlify PR 778 to the Fixed docs (sites/platform), following the pattern already used on the Redis page.

Changes

sites/platform/src/languages/nodejs/_index.md:

• Grid versions now use image-versions-live (sourced from meta.upsun.com) under Active, Sunset, and Decommissioned headings. This corrects Node.js 22, which was listed as deprecated; it's Active.
• Dedicated Gen 2 versions get their own section and keep the Supported/Deprecated lists from the registry.
• Links to #supported-versions now point to #active-versions.
• Yarn tab title changes from "Node.js 14" to "Node.js < 16".
• Bun examples use the latest active version instead of nodejs:20, which is now Sunset on Grid. Adds a note to choose an active version.

Differences from PR 778

• Decommissioned copy matches the Fixed Redis page ("existing projects continue to run as is, but all code pushes are blocked") rather than "no longer available".
• The shared Bun availability partial isn't changed, because the Upsun site also uses it.
• The service-list link fix doesn't apply: the Fixed page has no generated service list.

Testing

A clean hugo build of sites/platform completes without errors. Rendered lists: Active 26, 24, 22; Sunset 20 through 4; Decommissioned 0.12; Dedicated Gen 2 Supported 22, 20, 19 and Deprecated 18 through 9.8.

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