feat(todo): pick a place on a map, for quick add and a task's Where (ADR 0033, D32)

The location picker searches by city or district and name through
PlaceSearchGateway, its results a list and pins on Train's OpenFreeMap map,
or takes a pin placed by hand; recent places, and None, Arrive or Leave.
TodoDependencies.places is the seam for the instance's search; until then
komoot's public Photon, in a debug build asked for it alone. Quick add has
`+` suggestions, an entry in its + menu and a pin button; the task sheet a
Where box; a task's row the place's name.

ReminderScheduler plans the places to watch into LocationReminderGateway,
a no-op off Android, which TodoPerson.dispose clears, and Settings' Reminders
says while the device may not watch them.

Whats-New: Tasks can have locations: type + or use the + menu, search by city and name or pick on the map, and be reminded on arriving or leaving (Android).
Whats-New-De: Aufgaben können Orte haben: Tippe + oder nutze das +-Menü, suche nach Stadt und Name oder wähle auf der Karte, und lass dich beim Ankommen oder Verlassen erinnern (Android).
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/support/memory_location_gateway.dart

@@ -0,0 +1,41 @@
+import 'package:halkyon_todo_flutter/src/feature/location/data/location_reminder_gateway.dart';
+import 'package:halkyon_todo_flutter/src/feature/location/model/location_plan.dart';
+
+/// The device's watching of places, in memory, as a test can read it.
+class MemoryLocationGateway() implements LocationReminderGateway {
+  /// The places watched now.
+  List<LocationWatch> watched = const [];
+
+  /// What the device allows.
+  LocationAccess allowed = LocationAccess.always;
+
+  /// How often the places were handed over.
+  int replaced = 0;
+
+  @override
+  bool get available => true;
+
+  @override
+  Future<void> replace(
+    List<LocationWatch> watches, {
+    required String channel,
+  }) async {
+    watched = watches;
+    replaced++;
+  }
+
+  @override
+  Future<LocationAccess> access() async => allowed;
+
+  @override
+  Future<LocationAccess> askWhileInUse() async => allowed;
+
+  @override
+  Future<LocationAccess> askAlways() async => allowed;
+
+  @override
+  Future<void> openSettings() async {}
+
+  @override
+  Future<LatLon?> lastKnown() async => null;
+}