refactor: Extract event key Intent format to single source of truth

android/app/src/main/java/com/github/quarck/calnotify/app/ApplicationController.kt

@@ -976,17 +976,10 @@ object ApplicationController : ApplicationControllerInterface, EventMovedHandler
     ): SnoozeResult? {
         if (eventKeys.isEmpty()) return null
 
-        // Parse event keys into (eventId, instanceStartTime) pairs
-        val keyPairs = eventKeys.mapNotNull { key ->
-            val parts = key.split(":")
-            if (parts.size == 2) {
-                val eventId = parts[0].toLongOrNull()
-                val instanceStartTime = parts[1].toLongOrNull()
-                if (eventId != null && instanceStartTime != null) {
-                    Pair(eventId, instanceStartTime)
-                } else null
-            } else null
-        }.toSet()
+        // Parse event keys into (eventId, instanceStartTime) pairs using the shared format
+        val keyPairs = eventKeys.mapNotNull { EventAlertRecordKey.fromIntentString(it) }
+            .map { Pair(it.eventId, it.instanceStartTime) }
+            .toSet()
 
         return snoozeEvents(context, { event ->
             keyPairs.contains(Pair(event.eventId, event.instanceStartTime))

android/app/src/main/java/com/github/quarck/calnotify/calendar/EventAlertRecord.kt

@@ -110,7 +110,22 @@ fun Long.setFlag(flag: Long, value: Boolean)
         else
             this and flag.inv()
 
-data class EventAlertRecordKey(val eventId: Long, val instanceStartTime: Long)
+data class EventAlertRecordKey(val eventId: Long, val instanceStartTime: Long) {
+
+    /** Serialize for Intent extras */
+    fun toIntentString(): String = "$eventId:$instanceStartTime"
+
+    companion object {
+        /** Parse from Intent extras */
+        fun fromIntentString(key: String): EventAlertRecordKey? {
+            val parts = key.split(":")
+            if (parts.size != 2) return null
+            val eventId = parts[0].toLongOrNull() ?: return null
+            val instanceStartTime = parts[1].toLongOrNull() ?: return null
+            return EventAlertRecordKey(eventId, instanceStartTime)
+        }
+    }
+}
 
 data class EventAlertRecord(
         val calendarId: Long,

android/app/src/main/java/com/github/quarck/calnotify/ui/ActiveEventsFragment.kt

@@ -182,7 +182,7 @@ class ActiveEventsFragment : Fragment(), EventListCallback, SearchableFragment,
         val isChange = !hasActiveEvents
 
         // Pass selected event keys to SnoozeAllActivity via intent
-        val eventKeys = selectedEvents.map { "${it.eventId}:${it.instanceStartTime}" }.toTypedArray()
+        val eventKeys = selectedEvents.map { it.key.toIntentString() }.toTypedArray()
 
         // Get filter/search context for display
         val filterState = getFilterState()