Offline AI Assistant for Restaurant Costing, Inventory Analyses

I am a chef - need a secure, non-corruptible, offline AI assistant to handle core data workflows related to recipes, inventory, costing, and profit tracking.
A simple, solid, and easy-to-use AI-powered desktop app that works offline and can:

It should
Read & Understand:
Recipes with ingredients & quantities (Excel sheets)
Daily/weekly inventory Excel sheets (calculate costs, track consumption, generate weekly demand)
Sales data (item-wise, Excel sheets)
Purchase invoices (extract items, quantities, prices from PDF or photo, in Urdu & English)
Expense sheets (utilities, maintenance, payroll, etc. – Excel)

Calculate & Analyze:
Food cost per menu item (based on live rates + recipes)
Ideal vs. actual consumption (ingredients and supplies) using recipes + sales
Inventory updates with reorder suggestions
Profit & loss statements (revenues vs. food and operating costs)
Track item-level profitability (what’s making/lossing money)

Must Be Fully Offline - No internet required
Runs locally on Mac and Windows

Simple UI – no tech skills needed to operate


Please suggest the best tech stack combination for speed, stability, and offline performance.

Deliverables:
Fully working desktop tool (installer + source code)
Clear user guide
Setup support if needed (via screen share)

Please share:
Relevant past work
Tools/models you suggest using
A brief execution plan