feat(todo): reminders on the device, Upcoming's week strip, the task pane and search (ADR 0033, D2, D5, D8)

A task with a time takes reminders, minutes before it, in its sealed
payload; each device plans the coming ones whenever the tasks change and
schedules them with the system through flutter_local_notifications
(Android, iOS, macOS, Windows; on Linux the running app shows them), at
the minute where Android allows exact alarms. Notifying is asked for
when a task first gets a reminder; signing out or switching person
cancels them. Upcoming gets its week strip: the month opening
Material's calendar, the weeks before and after, a dot under each day
with tasks; a day picked scrolls the agenda to it, and scrolling moves
the strip along. From expanded windows on, a task opens in a pane
beside the list rather than in a dialog. Search, from every tab's app
bar, finds projects by name and tasks by every word typed, in their
title, description or labels, whatever the case and accents, on the
device 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/lib/l10n/app_de.arb

@@ -119,5 +119,23 @@
   "repeatEnds": "Endet",
   "repeatEndsNever": "Nie",
   "repeatEndsOn": "An einem Tag",
-  "repeatEndsAfter": "{count, plural, =1{Nach einem Mal} other{Nach {count} Malen}}"
+  "repeatEndsAfter": "{count, plural, =1{Nach einem Mal} other{Nach {count} Malen}}",
+  "remindersTitle": "Erinnerungen",
+  "remindersNone": "Keine Erinnerungen",
+  "reminderAtTime": "Zur Uhrzeit",
+  "reminderMinutesBefore": "{count, plural, =1{1 Minute vorher} other{{count} Minuten vorher}}",
+  "reminderHoursBefore": "{count, plural, =1{1 Stunde vorher} other{{count} Stunden vorher}}",
+  "reminderDaysBefore": "{count, plural, =1{1 Tag vorher} other{{count} Tage vorher}}",
+  "reminderDue": "Fällig um {time}",
+  "remindersChannel": "Erinnerungen an Aufgaben",
+  "remindersNotAllowed": "Benachrichtigungen sind für Halkyon Todo aus: Erinnerungen erscheinen, sobald du sie in den Systemeinstellungen erlaubst.",
+  "remindersOnThisDevice": "Erinnerungen kommen auf jedem deiner Geräte, das deine Aufgaben öffnet.",
+  "weekPrevious": "Vorige Woche",
+  "weekNext": "Folgende Woche",
+  "searchTitle": "Suchen",
+  "searchHint": "Aufgaben und Projekte suchen",
+  "searchEmpty": "Finde eine Aufgabe über die Wörter in ihrem Titel, ihrer Beschreibung oder ihren Labels. Die Suche läuft auf diesem Gerät: deine Instanz kann deine Aufgaben nicht lesen.",
+  "searchNone": "Nichts gefunden für „{query}“.",
+  "searchProjects": "Projekte",
+  "searchTasks": "Aufgaben"
 }