Use NaPTAN data for the UK stop finder

Import active NaPTAN stops into a local SQLite spatial index, including conversion of British National Grid coordinates. Add local searches, shareable stop links, source details and transport mode colours while retaining OSM route lookup by ATCO code.

Closes #1

tests/test_uk_bus_stops_playwright.py

@@ -320,3 +320,33 @@ def test_mobile_postcode_is_fitted_above_results_sheet(
     }""")
     assert 0 < position["markerY"] < position["visibleBottom"]
     page.close()
+
+
+def test_naptan_shared_stop_and_osm_routes(chromium_browser: Any, flask_url: str) -> None:
+    """NaPTAN links survive reload and show source fields plus matched OSM routes."""
+    page = chromium_browser.new_page(viewport={"width": 1280, "height": 800})
+    errors: list[str] = []
+    page.on("pageerror", lambda error: errors.append(str(error)))
+    stop = {
+        "type": "naptan", "source": "NaPTAN", "id": "0100BRP90317",
+        "lat": 51.44827, "lon": -2.58302, "name": "Temple Meads Stn",
+        "atco_code": "0100BRP90317", "indicator": "T1", "bearing": "SE",
+        "transport_type": "Bus stop", "tags": {"CommonName": "Temple Meads Stn", "Status": "active"},
+    }
+    page.route("**/api/stop/naptan/0100BRP90317", lambda route: route.fulfill(json={"stop": stop}))
+    page.route("**/api/stop/naptan/0100BRP90317/routes", lambda route: route.fulfill(json={
+        "matched_stops": 1, "routes": [{"id": 12, "ref": "A1", "name": "Airport bus"}],
+    }))
+    page.route("**/api/stops/in-bounds?*", lambda route: route.fulfill(json={"kind": "map", "stops": [stop]}))
+    page.goto(f"{flask_url}/?naptan=0100BRP90317")
+    expect = playwright_api.expect
+    for _ in range(2):
+        expect(page.locator("#stop-name")).to_have_text("Temple Meads Stn")
+        expect(page.locator("#stop-source")).to_contain_text("NaPTAN")
+        expect(page.locator("#tags-heading")).to_have_text("NaPTAN stop data")
+        expect(page.locator("#osm-link")).not_to_be_visible()
+        expect(page.locator("#route-list")).to_contain_text("A1")
+        assert "naptan=0100BRP90317" in page.url
+        page.reload()
+    assert errors == []
+    page.close()