fix(data): load bundled region packs in the browser; bound region lookups (#743)

The Natural Earth and neighborhood packs were loaded with a JSON-attributed
import(). The Vite dev server answers that request with a JavaScript module,
which the browser rejects, so every analyst region scope failed and fell
through to a geocode lookup that could take 12-28 s.

- src/data/bundledJson.js fetches the pack from a new URL(..., import.meta.url)
  asset in the browser; under Node the caller's attributed import runs.
- resolveRegionRingForQuery caps the geocode + admin-boundary rung at 3 s and
  returns { error: 'region-timeout' }; the lookup keeps running and fills the
  cache. The analyst query reports it as code 'region-timeout'. The Nepal
  locator opts out of the budget.
- Unit tests for the loader, the timeout and the analyst error; the behavior
  harness checks the Gulf of Mexico scope and retries Texas on region-timeout.

Co-authored-by: Bilawal Sidhu <[email protected]>

src/data/bundledJson.test.mjs

@@ -0,0 +1,36 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { loadBundledJson } from './bundledJson.js';
+
+const MARINE = new URL('./local_data/natural_earth/marine.json', import.meta.url);
+const importMarine = () =>
+  import('./local_data/natural_earth/marine.json', { with: { type: 'json' } });
+
+test('bundled JSON: a file URL uses the JSON import under Node', async (t) => {
+  const fetchMock = t.mock.method(globalThis, 'fetch');
+  const pack = await loadBundledJson(MARINE, importMarine);
+  assert.ok(pack.features.some((ft) => ft.name === 'Gulf of Mexico'));
+  assert.equal(fetchMock.mock.callCount(), 0);
+});
+
+test('bundled JSON: a served URL is fetched as plain JSON', async (t) => {
+  const requests = [];
+  t.mock.method(globalThis, 'fetch', async (url) => {
+    requests.push(String(url));
+    return new Response('{"features":[]}', {
+      headers: { 'content-type': 'application/json' },
+    });
+  });
+  const url = new URL('http://localhost/src/data/local_data/natural_earth/marine.json');
+  const importJson = () => assert.fail('the browser path must not import JSON');
+  assert.deepEqual(await loadBundledJson(url, importJson), { features: [] });
+  assert.deepEqual(requests, [url.href]);
+});
+
+test('bundled JSON: an HTTP error rejects so the retryable loader can retry', async (t) => {
+  t.mock.method(globalThis, 'fetch', async () => new Response('', { status: 404 }));
+  await assert.rejects(
+    loadBundledJson(new URL('http://localhost/missing.json'), importMarine),
+    /HTTP 404/,
+  );
+});