Discuss 'Isolated Modules' and its role in Transpiler Compatibility.

The 'isolatedModules' flag ensures that every file can be safely transpiled by tools like Babel or esbuild that don't perform type-checking.

Babel and esbuild operate on one file at a time; they don't know the full type graph. Certain TS features (like const enums or re-exporting types) require cross-file knowledge. Enabling 'isolatedModules' forces the TS compiler to error if you use these features in a way that would break single-file transpilation, ensuring your project remains compatible with high-performance build tools.