Bundle content scripts as IIFEs

[pascalbaljet]

Vite emits the multi-entry build-in ES module format, but the manifest loads content-script.js and page-world.js as classic scripts. Top-level bindings in a classic script land in the scope it runs in, so every minified name in the bundle became a global (var e, var t, var n, etc.). For page-world, which runs in the MAIN world, that scope is the inspected page's own.

Any page whose scripts declare a colliding top-level let then fails to parse, not merely at runtime. On reddit.com, our global e broke their first inline script with "Identifier 'e' has already been declared", which took out the helper the rest of their inline scripts call, and infinite scroll stopped loading posts entirely.

Content scripts now build as separate single-entry IIFE bundles, the same way the service worker is already built, so nothing escapes into the page. The build fails if either bundle stops opening as an IIFE.