feat: display actual reminder schedule from server config (#386)

- Expose REMINDER_HOUR and REMINDER_MINUTES_BEFORE env values via settings API
- Add reminderHour and reminderMinutesBefore to frontend Settings interface
- Replace hardcoded i18n strings with parameterized translations
- Settings page now shows configured schedule instead of static 6:00 / 15 min

frontend/src/i18n/de.json

@@ -323,9 +323,9 @@
     "schedule": {
       "title": "Erinnerungsplan",
       "stockCheck": "Bestands- & Rezeptprüfung",
-      "dailyAt6": "Täglich um 6:00 Uhr",
+      "dailyAtHour": "Täglich um {{hour}}:00 Uhr",
       "intakeCheck": "Einnahmeprüfung",
-      "15minBefore": "15 Min. vor geplanter Zeit",
+      "minutesBefore": "{{minutes}} Min. vor geplanter Zeit",
       "nextCheck": "Nächste Bestandsprüfung",
       "lastSent": "Letzte Benachrichtigung",
       "lastStockSent": "Letzte Bestands-Erinnerung",

frontend/src/i18n/en.json

@@ -323,9 +323,9 @@
     "schedule": {
       "title": "Reminder Schedule",
       "stockCheck": "Stock & prescription check",
-      "dailyAt6": "Daily at 6:00 AM",
+      "dailyAtHour": "Daily at {{hour}}:00",
       "intakeCheck": "Intake check",
-      "15minBefore": "15 min before scheduled time",
+      "minutesBefore": "{{minutes}} min before scheduled time",
       "nextCheck": "Next stock check",
       "lastSent": "Last notification sent",
       "lastStockSent": "Last stock reminder",