feat(todo): dialogs on the desktop, the tabs reordered, a task's path and menu (ADR 0033, D11 to D14)

- halkyon_ui: showAdaptiveSheet shows a dialog on Linux, macOS and Windows
  at every width (bottom sheets stay on phones and tablets below expanded
  windows), so Learn and Train follow; SheetScaffold takes a heading in
  the title's place and may leave out its close button.
- Todo: the tabs are Inbox, Today, Upcoming, Browse, Today still opening;
  `serverpod start` launches the app on Linux, as it has no web build.
- A task's sheet shows where the task is (its project, an icon once tasks
  are above it, and the tasks above it, each opening what it names) and a
  ⋮ menu in place of its close button: when it was added (its UUID v7),
  Duplicate with its sub-tasks, hiding its done sub-tasks (synced in its
  payload), Close in the pane, Delete after asking. The description's icon
  stays by its first line.
- A row names its project and section at the end of its date's line; every
  menu entry has its icon.
- Learn: a studyset's path starts at the Library tab's icon, named by its
  tooltip.

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

@@ -137,5 +137,13 @@
   "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"
+  "searchTasks": "Aufgaben",
+  "taskMore": "Optionen der Aufgabe",
+  "taskAddedOn": "Hinzugefügt am {when}",
+  "taskDuplicate": "Duplizieren",
+  "taskDuplicated": "Aufgabe dupliziert",
+  "subTasksHideDone": "Erledigte Unteraufgaben ausblenden",
+  "subTasksShowDone": "Erledigte Unteraufgaben zeigen",
+  "taskClose": "Schließen",
+  "taskPath": "Wo die Aufgabe liegt"
 }