One-Page Admin Price Chart

I need a lightweight, single-page web app that only I can access. Its core job is simple: I drop an Excel or CSV file on the page, hit “Upload,” and the system parses the data and instantly refreshes a price chart on the same screen. No manual editing will be done online—every change comes from the spreadsheet.

Flow
1. Secure admin-only login (basic auth is fine).
2. Drag-and-drop or file-picker upload for .xlsx and .csv.
3. Server processes the file, stores the data, and clears the previous set so the display is always in sync with the most recent upload.
4. The refreshed data appears visually (line or bar chart—open to whichever library you prefer, e.g., Chart.js, D3) and in a simple table below it.
5. Option to download the current dataset as CSV for quick backup.

Tech stack is flexible; a small PHP, Python Flask, or Node solution with a lightweight database (SQLite or MySQL) will do the trick. Clean code and clear setup instructions are all I need to deploy it on my own hosting.