Super Speedy Imports v2.55.9

* **Products now get assigned every level of a category path, not just the deepest one.** When a product is in <code>Men &gt; T-Shirts</code>, WooCommerce expects BOTH <code>Men</code> and <code>T-Shirts</code> to be attached to it — that's what WP All Import does, and it's what makes <code>/product-category/men/</code> list the product, breadcrumbs render the full path, and layered-navigation filters include parent categories. SSI previously assigned only the leaf term (<code>T-Shirts</code>), so parent category pages showed nothing. This was the single biggest functional difference between SSI and WPAI in our benchmark comparisons. There's a new **Assign every category level** option in Additional Options to control it. **New imports default it ON.** Existing imports created before this release keep their previous leaf-only behaviour until you switch it on, so nothing changes under you on a re-run unless you opt in. This replaces the undocumented `SSI_ADD_ALL_TERMS_FROM_HIERARCHY` PHP constant, which no longer has any effect. See `.docs/2026-05-26-leaf-vs-all-level-term-assignment.md`.