fix: emit "use strict" everywhere to thwart bad bundlers

[thejustinwalsh]

When running vite as my bundler, koota is running under strict mode.
When using metro with expo dom components koota is not running under strict mode.

When this is evaluated in Number.prototype.add in strict mode it will be a number.
When this is evaluated in Number.prototype.add without strict mode, it is coerced into an object, and that object is then used as the lookup in the Set where that object is not in the Set, the valueOf that object is.

See: https://262.ecma-international.org/5.1/#sec-C

Philosophcally it is a slightly painful pr to make, however, if bundlers in 2025 are going to run esm code without strict mode enabled, we should help them to have a chance.

[thejustinwalsh]

Configuring metro to use experimentalImportSupport resolves this issue, and correctly emits "use strict"; in the final bundle. As of Expo SDK 53, this is not the default config.

Enable experimentalImportSupport to your metro.config.js:

config.transformer.getTransformOptions = () => ({
  transform: {
    experimentalImportSupport: true,
  },
});

It is worth noting that experimentalImportSupport doesn't currently support require cycles or destructuring.

[krispya]

Could you add a comment on this tsup setting explaining why it exists? It is okay for it to be long-winded, having documentation in the code will make Koota easier to maintain in the future.