OPFS + Pyodide test harness

- **Simon Willison** is a well-known web developer and creator of Datasette, an open-source Python tool for exploring and publishing tabular data (especially SQLite databases). He regularly experiments with browser-based computing. - **Pyodide** is a Python runtime that runs entirely in the browser via WebAssembly — it lets you execute Python code on a web page without a server. - **Datasette Lite** is a browser-only version of Datasette that uses Pyodide, so users can open and query SQLite databases entirely client-side. - **Origin Private File System (OPFS)** is a modern browser API that gives web applications a private, sandboxed file system for reading and writing files locally — it is faster and more capable than earlier browser storage APIs, and crucially supports synchronous writes, which Python's SQLite library requires. - The key question here: can Datasette Lite combine OPFS with Pyodide to allow users to open, edit, and save SQLite database files on their own computer, all within the browser? This test harness is a quick experiment (built with the help of Claude Code, Anthropic's AI coding tool) to check what browser support looks like.