feat(train): reminders to move and workouts suggested from the steps (ADR 0037)

Settings' Moving more, on Android: a reminder to get up after an idle
time, and a suggested walk or run, each off until turned on (then every
30 minutes, weekdays 9:00 to 18:00, not 12:00 to 13:00, each value the
person's), turning on asking for the activity and notification
permissions.

A WorkManager job every 15 minutes reads the phone's step counter and
keeps two hours of readings. It reminds where fewer than 50 steps came
over the idle time, all of it within the hours and outside the break,
on the person's days, never while Train records or the phone is in a
car (Android's car mode, or a car's Bluetooth audio or hands-free). It
suggests a walk or a run where the last span averaged a walking or
running cadence, once an hour; tapped, the Record sheet for it opens.
The decisions are pure Kotlin (Movement.kt), tested on the JVM; the
notifications' words are the app's, written into the job's
configuration as the person's app opens.

Polar's SDK sets neither the band's inactivity alert nor tells of one
without an all-day connection, hence the phone's steps (ADR 0037).

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/train/halkyon_train_flutter/test/support/fake_movement_platform.dart

@@ -0,0 +1,26 @@
+import 'dart:async';
+
+import 'package:halkyon_train_flutter/src/feature/movement/data/movement_platform.dart';
+import 'package:halkyon_train_flutter/src/feature/workout/model/workout.dart';
+
+/// The phone's side of Moving more as a test wants it (ADR 0037): whether
+/// it counts steps, each configuration the job got, and suggestions tapped
+/// by [tap].
+class FakeMovementPlatform({var bool counts = true})
+    implements MovementPlatform {
+  final configured = <Map<String, Object?>?>[];
+  final _openings = StreamController<Activity>.broadcast();
+
+  /// A suggestion of [activity] tapped.
+  void tap(Activity activity) => _openings.add(activity);
+
+  @override
+  Future<bool> available() async => counts;
+
+  @override
+  Future<void> configure(Map<String, Object?>? config) async =>
+      configured.add(config);
+
+  @override
+  Stream<Activity> openings() => _openings.stream;
+}