product_variant_multi_link
Extend product multi-linking to operate on specific product variants rather than only on templates.
Key Features
- product.template.link: Adds variant-side fields with validation and duplicate checks so each link pairs explicit source and target variants while keeping cache invalidation in sync.
- product.product: Provides computed access to related variant links, counts them, and exposes a smart button that opens those links.
- product.template.link: Updates the search, list, kanban, and form views to let users pick variants tied to the chosen templates and filter links by variant.