feat: Add Clear Missed Doses feature (#28)

- Add dismissed column to dose_tracking table schema
- Add POST /doses/dismiss endpoint for batch dismissing
- Add DELETE /doses/dismiss endpoint to un-dismiss all
- Add frontend dismissedDoses state and missedPastDoseIds useMemo
- Add Clear missed button with confirmation dialog
- Add CSS styles for .past-days-header and .clear-missed-btn
- Add i18n translations for en/de
- Add 5 tests for dismiss endpoints
- Update test schemas with dismissed column

Allows users to acknowledge missed doses without deducting stock.
Closes #28

frontend/src/i18n/de.json

@@ -38,7 +38,14 @@
       "pastDaysCount": "{{count}} Tag",
       "pastDaysCount_other": "{{count}} Tage",
       "missedDoses": "{{count}} verpasste Dosis",
-      "missedDoses_other": "{{count}} verpasste Dosen"
+      "missedDoses_other": "{{count}} verpasste Dosen",
+      "clearMissed": "Verpasste löschen",
+      "clearMissedConfirmTitle": "Verpasste Dosen löschen?",
+      "clearMissedConfirmMessage": "{{count}} verpasste Dosis wird als bestätigt markiert, ohne vom Bestand abgezogen zu werden.",
+      "clearMissedConfirmMessage_other": "{{count}} verpasste Dosen werden als bestätigt markiert, ohne vom Bestand abgezogen zu werden.",
+      "clearMissedConfirm": "Ja, löschen",
+      "clearMissedCancel": "Abbrechen",
+      "clearMissedSuccess": "{{count}} verpasste Dosen gelöscht"
     },
     "reminders": {
       "active": "Automatische Erinnerungen aktiv",

frontend/src/i18n/en.json

@@ -40,7 +40,14 @@
       "pastDaysCount": "{{count}} day",
       "pastDaysCount_other": "{{count}} days",
       "missedDoses": "{{count}} missed dose",
-      "missedDoses_other": "{{count}} missed doses"
+      "missedDoses_other": "{{count}} missed doses",
+      "clearMissed": "Clear missed",
+      "clearMissedConfirmTitle": "Clear Missed Doses?",
+      "clearMissedConfirmMessage": "This will mark {{count}} missed dose as acknowledged without deducting from your stock.",
+      "clearMissedConfirmMessage_other": "This will mark {{count}} missed doses as acknowledged without deducting from your stock.",
+      "clearMissedConfirm": "Yes, Clear",
+      "clearMissedCancel": "Cancel",
+      "clearMissedSuccess": "Cleared {{count}} missed doses"
     },
     "reminders": {
       "active": "Automatic reminders active",