feat(home): localize greetings and address profile names

lib/utils/home_greeting.dart

@@ -0,0 +1,45 @@
+import 'dart:math';
+
+import 'package:spotiflac_android/l10n/app_localizations.dart';
+
+/// Picked once per launch: the greeting holds still while browsing and
+/// changes the next time the app opens.
+final int _sessionVariant = Random().nextInt(1 << 16);
+
+/// A time-of-day Home greeting, addressed by the profile's first name when
+/// one is set.
+String homeGreeting(
+  AppLocalizations l10n, {
+  String name = '',
+  DateTime? now,
+  int? variant,
+}) {
+  final hour = (now ?? DateTime.now()).hour;
+  final options = switch (hour) {
+    >= 5 && < 12 => [
+      l10n.homeGreetingMorning1,
+      l10n.homeGreetingMorning2,
+      l10n.homeGreetingMorning3,
+    ],
+    >= 12 && < 17 => [
+      l10n.homeGreetingAfternoon1,
+      l10n.homeGreetingAfternoon2,
+      l10n.homeGreetingAfternoon3,
+    ],
+    >= 17 && < 21 => [
+      l10n.homeGreetingEvening1,
+      l10n.homeGreetingEvening2,
+      l10n.homeGreetingEvening3,
+    ],
+    _ => [
+      l10n.homeGreetingNight1,
+      l10n.homeGreetingNight2,
+      l10n.homeGreetingNight3,
+    ],
+  };
+  final phrase = options[(variant ?? _sessionVariant) % options.length];
+  final trimmed = name.trim();
+  if (trimmed.isEmpty) return phrase;
+  // A full name reads stiff in a headline.
+  return l10n.homeGreetingNamed(phrase, trimmed.split(RegExp(r'\s+')).first);
+}