feat(url): implement URL.searchParams property

[akapug]

Summary

Implements the searchParams property on URL objects by parsing the query string into a URLSearchParams instance.

Previously, accessing url.searchParams threw NotImplementedError. Now it returns a properly populated URLSearchParams object.

Example

const url = new URL('http://example.com?foo=bar&baz=qux');
url.searchParams.get('foo');  // 'bar'
url.searchParams.has('baz');  // true

for (const [key, value] of url.searchParams) {
  console.log(`${key} = ${value}`);
}

Why This Matters

Server-side code using the fetch handler pattern needs to parse query parameters from incoming requests:

export default {
  async fetch(request: Request): Promise<Response> {
    const url = new URL(request.url);
    const text = url.searchParams.get('text');  // ❌ Was throwing NotImplementedError
    // ...
  }
}

Without searchParams.get(), developers must manually parse the query string, which is error-prone and inconsistent with the URL spec.

Changes

• URLIntrinsic.kt: Implement computeSearchParams() to parse query string into URLSearchParams

Testing

Tested locally with Elide beta11-rc3:

const url = new URL("http://localhost:8080/analyze?text=hello&foo=bar");
console.log(url.searchParams.get('text'));  // Now works!

cc @darvld - this is a simple 6-line fix for a TODO that was blocking server-side URL parsing.

[darvld]

CI failures are unrelated, changes are good