Introduce a shared InventoryDuplicateMatcher (SKU, manufacturer part number,
manufacturer color) used by both manual inventory creation and powder-label
scanning, so the two paths flag duplicates consistently. Surfaces a duplicate
warning in the Create/Edit forms via inventory-duplicate-check.js and the
catalog-lookup / label-scan flows. Callers pass tenant-restricted inventory;
the matcher re-checks CompanyId as defense in depth.
Adds InventoryDuplicateMatcherTests covering the match precedence.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
