feat(todo): a location's search goes through the instance (ADR 0033, D32)

The picker now searches with the server's `search`, and says search
isn't available where the instance has no Photon rather than that it
failed. A debug build may still ask for komoot's public one, for an
instance without. A point on the map stays unnamed through the instance,
which searches by name alone.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

apps/todo/halkyon_todo_flutter/test/feature/location/location_picker_test.dart

@@ -8,7 +8,8 @@ import 'package:halkyon_todo_flutter/src/feature/location/model/task_location.da
 import 'package:halkyon_todo_flutter/src/feature/location/widget/location_picker.dart';
 import 'package:material_ui/material_ui.dart';
 
-class _Places(final List<TaskLocation> found) implements PlaceSearchGateway {
+class _Places(final List<TaskLocation> found, {final bool isOffered = true})
+    implements PlaceSearchGateway {
   final asked = <String>[];
   LatLon? near;
 
@@ -25,6 +26,9 @@ class _Places(final List<TaskLocation> found) implements PlaceSearchGateway {
 
   @override
   Future<TaskLocation?> at(LatLon point, {String? language}) async => null;
+
+  @override
+  Future<bool> offered() async => isOffered;
 }
 
 /// The location picker (ADR 0033, D32), without tiles.
@@ -132,6 +136,21 @@ void main() {
     expect(find.byKey(locationMapKey), findsOneWidget);
   });
 
+  testWidgets('an instance without a search says so, the map stays', (
+    tester,
+  ) async {
+    await open(tester, places: _Places(const [], isOffered: false));
+    await tester.pump();
+    expect(find.byKey(locationSearchKey), findsNothing);
+    expect(
+      find.text(
+        "Search isn't available here. Move the map and tap to place a pin.",
+      ),
+      findsOneWidget,
+    );
+    expect(find.byKey(locationMapKey), findsOneWidget);
+  });
+
   testWidgets('recent places show before a search', (tester) async {
     await open(tester, places: _Places(const []), recents: const [aeschach]);
     expect(find.text('Recent'), findsOneWidget);

apps/todo/halkyon_todo_flutter/test/feature/location/place_search_test.dart

@@ -1,8 +1,72 @@
+import 'package:halkyon_todo_client/halkyon_todo_client.dart';
 import 'package:halkyon_todo_flutter/src/feature/location/data/place_search_gateway.dart';
 import 'package:test/test.dart';
 
 /// Replies as Photon's (ADR 0033, D32).
 void main() {
+  test("the instance's places keep their address and object", () async {
+    final gateway = InstancePlaceSearch(
+      asked: () async => true,
+      find: (query, near, language) async {
+        expect((query, near?.lat, language), ('Lindau EDEKA', 47.5, 'de'));
+        return [
+          Place(
+            name: 'EDEKA',
+            detail: 'Ludwig-Kick-Straße 1, Lindau',
+            kind: 'house',
+            osmType: 'N',
+            osmId: 7,
+            lat: 47.55,
+            lon: 9.7,
+          ),
+        ];
+      },
+    );
+    final [place] = await gateway.search(
+      'Lindau EDEKA',
+      near: (lat: 47.5, lon: 9.7),
+      language: 'de',
+    );
+    expect(place.address, 'Ludwig-Kick-Straße 1, Lindau');
+    expect((place.lat, place.lon), (47.55, 9.7));
+    expect((place.osmType, place.osmId), ('N', 7));
+  });
+
+  test('a place without a detail has no address', () async {
+    final gateway = InstancePlaceSearch(
+      asked: () async => true,
+      find: (_, _, _) async => [
+        Place(name: 'Lindau', kind: 'city', lat: 47.55, lon: 9.7),
+      ],
+    );
+    final [place] = await gateway.search('Lindau');
+    expect(place.address, '');
+  });
+
+  test("an instance that can't be asked offers no search", () async {
+    final gateway = InstancePlaceSearch(
+      asked: () async => throw Exception('offline'),
+      find: (_, _, _) async => const [],
+    );
+    expect(await gateway.offered(), isFalse);
+  });
+
+  test('a refusal reaches the picker, which says the search failed', () {
+    final gateway = InstancePlaceSearch(
+      asked: () async => true,
+      find: (_, _, _) async => throw SearchRefused(reason: 'unreachable'),
+    );
+    expect(gateway.search('Lindau'), throwsA(isA<SearchRefused>()));
+  });
+
+  test('a point on the map has no name from the instance', () async {
+    final gateway = InstancePlaceSearch(
+      asked: () async => true,
+      find: (_, _, _) async => const [],
+    );
+    expect(await gateway.at((lat: 47.5, lon: 9.7)), isNull);
+  });
+
   Map<String, Object?> feature(
     Map<String, Object?> properties, {
     List<num> at = const [9.70, 47.55],