feat(home): move "use my location" beside the hero search box

The geolocation shortcut lived in the discovery strip below the results,
away from the search. Move it directly under the hero search input, paired
with the postcode hint, so the two ways to find nearby schools ("type a
postcode" / "use my location") read as one idea and are visible at first
glance.

- FilterBar gains optional onNearMe/geoState/geoError props and renders the
  teal "Use my location" pill (with spinner + error) in hero mode; the
  geolocation flow itself still lives in HomeView.
- Remove the now-duplicate near-me button and its dead CSS from the
  discovery section.
- Refresh the search hint copy to pair with the button.
- e2e: assert the "use my location" shortcut renders in the hero.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

e2e/tests/journeys.spec.ts

@@ -25,6 +25,16 @@ test('home page loads with hero search', async ({ page }) => {
   await expect(page.getByPlaceholder('School name or postcode').first()).toBeVisible();
 });
 
+test('home hero offers a "use my location" shortcut beside the search box', async ({ page }) => {
+  await page.goto('/');
+  // The geolocation shortcut lives inside the hero search card, right under the
+  // search input — not in a separate strip further down the page.
+  const searchInput = page.getByPlaceholder('School name or postcode').first();
+  await expect(searchInput).toBeVisible();
+  const nearMe = page.getByRole('button', { name: /use my location/i });
+  await expect(nearMe).toBeVisible();
+});
+
 test('searching by name returns school results', async ({ page }) => {
   await searchByName(page, 'primary');
   await expect(schoolLinks(page).first()).toBeVisible({ timeout: 15_000 });