Modernize toolchain

[jill64]

Modernize and update the Svelte tool chain to reduce the occurrence of problems like #52 and #54. Specifically, the changes include

1. Update Dependencies

package	version
@sveltejs/adapter-auto	next => 3.x
@sveltejs/kit	next => 2.x
@sveltejs/package	next => 2.x
prettier	2.x => 3.x
svelte	3.x => 4.x
svelte-check	2.x => 3.x
vite	3.x => 5.x

2. New Dependencies

• @jill64/eslint-config-svelte
  • for ESLint flat config
• @sveltejs/vite-plugin-svelte
  • for svelte pre-process

3. Update npm run build

   • Remove temporary patch script
   • Add publint step

4. Add exports and files fields to package.json.

There are no changes to the library's public content. These reduce the burden for future updates.

Also, after updating, library publication to npm is completed only with npm publish.