feat(meditate): the app: Today, Explore, Profile, the sitting and its bells

halkyon_meditate_flutter on halkyon_app and halkyon_ui (ADR 0038): the
first start, sign-in and account as every Halkyon app's, a bar below
medium windows and a rail with the icon from medium on, fern washes,
Settings in cards (Sync, the operator's, Sitting, Practice, the
account, What's new, About, the version), English and German.

- Today: a greeting by the hour, Sit now at 5, 10, 20 minutes and the
  timer's own length, the practice of the day, the week with the days
  in a row, favourites, recently sat (D9).
- Explore: six practices of Halkyon's own, written for the app, found
  by a search without case or accents, by goal and by kind; each page
  with how it goes, its lengths, its heart and Start (D4, D10).
- The sitting, over the tabs: its time from the clock, a ring counting
  down, the cue of the moment, Pause and End, the bells at the start,
  between and at the end, the screen kept on; ended early, kept from a
  minute on where the person says so (D5, D6).
- Profile: every Halkyon app's, then the person's practice: minutes,
  sittings, days, the week and every sitting kept, to delete (D8).
- Settings and sittings sealed with the person's key and synced (D7).

The bells are synthesised by apps/meditate/tool/bells.py, the icon is
Lucide's sprout from cobalt through pacific into fern
(tool/app_icons.py). Releases and the deploy are a later step.

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/meditate/halkyon_meditate_flutter/lib/main.dart

@@ -0,0 +1,51 @@
+import 'dart:io';
+
+import 'package:flutter/services.dart';
+import 'package:halkyon_app/halkyon_app.dart';
+import 'package:halkyon_meditate_flutter/src/app/licences.dart';
+import 'package:halkyon_meditate_flutter/src/app/meditate_app.dart';
+import 'package:halkyon_meditate_flutter/src/app/meditate_dependencies.dart';
+import 'package:halkyon_ui/halkyon_ui.dart';
+import 'package:material_ui/material_ui.dart';
+import 'package:path/path.dart' as p;
+import 'package:serverpod_flutter/serverpod_flutter.dart';
+
+Future<void> main() async {
+  WidgetsFlutterBinding.ensureInitialized();
+  // Noto Sans' notice (halkyon_ui), the flags' and Unicode CLDR's
+  // (halkyon_app), and Lucide's for the app's icon.
+  registerFontLicenses();
+  registerHalkyonAppLicenses();
+  registerLucideLicense();
+  // The instance the build names (`--dart-define=SERVER_URL=…`, or
+  // `assets/config.json`): the first offered at the first start.
+  final builtIn = Instance.parse(await getServerUrl())!;
+  final device = await MeditateDevice.create(builtIn: builtIn);
+  final instances = InstanceChoice(
+    FileInstanceStore(File(p.join(device.support, 'instances.json'))),
+    builtIn: builtIn,
+    forget: device.storage.forget,
+    sharesStorage: device.storage.sharesWith,
+  );
+  await instances.load(usedBefore: device.storage.usedBefore());
+  runApp(
+    // What's new in each release (Train's ADR 0030, D61), from
+    // assets/whats_new/, shown once after an update.
+    WhatsNewScope(
+      whatsNew: WhatsNew(
+        AssetWhatsNewSource(rootBundle),
+        FileWhatsNewStore(File(p.join(device.support, 'whats_new.json'))),
+        version: device.appVersion,
+      ),
+      // An instance chosen before: the app ran on this device already.
+      usedBefore: instances.current != null,
+      child: MeditateApp(
+        choice: instances,
+        // Only an instance of Halkyon Meditate: one of another Halkyon app's
+        // answers too, but holds nothing of this app's.
+        checker: ServerpodInstanceChecker(app: 'meditate'),
+        open: (instance) => MeditateDependencies.create(instance, device),
+      ),
+    ),
+  );
+}