Use formatter for LLS duration

libraries/dateformatter/api/src/main/kotlin/io/element/android/libraries/dateformatter/api/DurationFormatter.kt

@@ -11,6 +11,19 @@ package io.element.android.libraries.dateformatter.api
 import java.util.Locale
 import kotlin.time.Duration
 
+/**
+ * Formats a duration in a localized, human-readable way.
+ * Uses the largest appropriate unit (hours, minutes, or seconds).
+ *
+ * Examples (in English):
+ * - 2 hours 30 minutes → "3 hours" (rounded)
+ * - 45 minutes → "45 minutes"
+ * - 30 seconds → "30 seconds"
+ */
+interface DurationFormatter {
+    fun format(duration: Duration): String
+}
+
 /**
  * Convert milliseconds to human readable duration.
  * Hours in 1 digit or more.