Add an Add-item button to the Inventory page that opens a COSS form dialog
(name required; form, strength, stock, reorder point, location, expiry). On
submit it persists via createInventory and prepends the saved row so it
appears immediately. Mirrors the appointments add-dialog pattern.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Khalid Abdi