fix: correct housekeeping module bugs after merge

- Restore migration order: remove spurious v30 birthday-reminders entry
  inserted before CardDAV (v30) and birthday-reminders (v31), which caused
  a duplicate v31 on fresh installs
- Restore birthdayReminderAt() offsetMin handling (regression from merge)
- Fix check-in INSERT: check_out was set to checkIn instead of NULL,
  making sessions invisible to loadOpenSession (IS NULL query)
- Implement check-out path in toggleSession() — only check-in was reachable
- Wrap GET /task-templates in try/catch per project convention
- Fix DELETE response envelopes: { ok: true } → { data: ... }
- Remove housekeeping worker exclusion from GET /auth/users
- Replace toISOString() with local-date helper to avoid UTC date shift
- Use user currency preference in money() instead of hardcoded BRL
- Replace hardcoded #7C3AED fallbacks in style attrs with CSS token
- Add German translations for documents folder and settings housekeeping keys
- Remove DESIGN.md and IMPLEMENTATION.md (AI planning artifacts)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

public/locales/de.json

@@ -1062,11 +1062,11 @@
     "helpTooltipCardDAV": "CardDAV ermöglicht die Synchronisation von Kontakten mit iCloud, Nextcloud und anderen CardDAV-Servern.",
     "emptyStateAddFirst": "Füge dein erstes Konto hinzu",
     "emptyStateNoAccounts": "Noch keine Konten verbunden",
-    "sectionHousekeeping": "Housekeeping",
-    "housekeepingPaymentsTitle": "Payment tasks",
-    "housekeepingPaymentTasksLabel": "Create a payment task on each housekeeper check-in",
-    "housekeepingPaymentTasksHint": "When enabled, each check-in creates a task for paying the staff member. Completing that task marks the visit payment as paid.",
-    "housekeepingPaymentTasksSaved": "Housekeeping payment setting saved."
+    "sectionHousekeeping": "Haushaltshilfe",
+    "housekeepingPaymentsTitle": "Zahlungsaufgaben",
+    "housekeepingPaymentTasksLabel": "Bei jedem Einchecken eine Zahlungsaufgabe erstellen",
+    "housekeepingPaymentTasksHint": "Wenn aktiviert, wird bei jedem Einchecken eine Aufgabe zur Bezahlung der Haushaltshilfe erstellt. Das Erledigen dieser Aufgabe markiert den Besuch als bezahlt.",
+    "housekeepingPaymentTasksSaved": "Einstellung für Haushaltshilfe-Zahlungen gespeichert."
   },
   "login": {
     "tagline": "Familienplanung. Sicher. Datenschutzfreundlich. Open Source.",
@@ -1298,14 +1298,14 @@
     "dropzoneTitle": "Datei hier ablegen oder klicken",
     "dropzoneHint": "Ziehe eine Datei in diesen Bereich oder nutze die Dateiauswahl.",
     "selectedFileLabel": "Ausgewählt: {{name}}",
-    "addFolderButton": "Add folder",
-    "allFolders": "All folders",
-    "folderLabel": "Folder",
-    "noFolder": "No folder",
-    "newFolderTitle": "New folder",
-    "folderNameLabel": "Folder name",
-    "createFolderAction": "Create folder",
-    "folderCreatedToast": "Folder created.",
+    "addFolderButton": "Ordner hinzufügen",
+    "allFolders": "Alle Ordner",
+    "folderLabel": "Ordner",
+    "noFolder": "Kein Ordner",
+    "newFolderTitle": "Neuer Ordner",
+    "folderNameLabel": "Ordnername",
+    "createFolderAction": "Ordner erstellen",
+    "folderCreatedToast": "Ordner erstellt.",
     "housekeepingFolder": "Hausreinigung",
     "calendarItemsFolder": "Kalendereinträge",
     "folderBrowserTitle": "Ordner durchsuchen"