feat: cache rails.wasm

[Bakaface]

This PR implements the caching of rails.wasm in OPFS. The algorithm is the following:

• In template (webcontainer environment):

  • If ./rails-<package_version>.wasm file is not present, install @rails-tutorial/wasm package.
  • Else, move the file into node_modules/@rails-tutorial/wasm/dist/rails.wasm.

• In astro (browser environment):

  • If rails-<package_version>.wasm is present in OPFS, read the file and write it to webcontainer filesystem as rails-<package_version>.wasm.
  • Else, start the caching process:
    • Poll every 1 second for /node_modules/@rails-tutorial/wasm/dist/rails.wasm in webcontainer
    • Once the file is available, read it from webcontainer
    • Persist it to OPFS as rails-<package_version>.wasm for future use

Use the following script to clear the cache during testing:

(async () => {
	try {
		const opfsRoot = await navigator.storage.getDirectory();
		await opfsRoot.removeEntry('rails-8.0.2-rc.1.wasm');
	} catch (error) {
		console.log('No cached file to clear or error:', error);
	}
})();

Resolves #9

[palkan]

Amazing!

Checked locally—no issues! Let's see how it does in production.