Nerve FFMS

A rewrite of the point-of-sale terminal as a desktop application, because a browser tab is a bad way to run a till that has to survive a dropped network cable mid-transaction. Tauri v2 gives a small binary that opens instantly and keeps working offline. It carries the whole operational surface: PIN login with role-based screen permissions for owner, manager, cashier and kitchen; a cart with variants, add-ons and held carts; inventory that deducts through recipes rather than raw line items, so a slice of cake removes the right amount of flour; a kitchen queue with a separate phone screen; and ESC/POS thermal printing for both receipts and kitchen tickets. Payments go out as dynamic Raast QR codes, generated per transaction with the till and the account title baked in.