fix: Keep the paused point as audio finishes

A pause just as a sentence finished could lose the listener's place.
The audio had finished, but playback had not yet reported completion,
so resuming could repeat the whole sentence instead of its final second.

Kept the heard position available through that brief handoff, until
playback stopped or the next sentence began. Added a regression test
that reproduced the lost position before the fix and checked it for
both a full sentence and audio resumed partway through a sentence.

app/src/main/kotlin/com/chmouel/liseur/tts/PcmOutput.kt

@@ -51,6 +51,7 @@ class AudioTrackPcmOutput(
     private var applied = 1f
 
     /** The clip of the current turn: where its frames start on the track's head, and its bounds. Under [lock]. */
+    // Retain it through completion: a pause can precede the handoff back to the engine.
     private var clip: Clip? = null
 
     /** The speed the track plays at, set to [speed] first. Under [lock]. */
@@ -146,7 +147,6 @@ class AudioTrackPcmOutput(
             val (head, rate) = synchronized(lock) {
                 if (turn != myTurn) return@withContext
                 val head = track.playbackHeadPosition.toLong() and 0xffffffffL
-                if (head >= target && clip === playing) clip = null
                 head to speedLocked(track)
             }
             if (head >= target) return@withContext

app/src/test/kotlin/com/chmouel/liseur/tts/PcmOutputTest.kt

@@ -0,0 +1,32 @@
+package com.chmouel.liseur.tts
+
+import android.app.Application
+import kotlinx.coroutines.test.StandardTestDispatcher
+import kotlinx.coroutines.test.runTest
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNull
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.robolectric.RobolectricTestRunner
+import org.robolectric.annotation.Config
+
+@Config(sdk = [35], application = Application::class)
+@RunWith(RobolectricTestRunner::class)
+class PcmOutputTest {
+    @Test
+    fun completedAudioKeepsItsHeardPositionUntilHalted() = runTest {
+        val output = AudioTrackPcmOutput(writer = StandardTestDispatcher(testScheduler))
+        val frames = 3 * SpeechAudio.SAMPLE_RATE
+        val pcm = ByteArray(frames * 2)
+        try {
+            output.play(pcm)
+            assertEquals(frames, output.halt())
+            assertNull(output.halt())
+
+            output.play(pcm, fromFrame = SpeechAudio.SAMPLE_RATE)
+            assertEquals(frames, output.halt())
+        } finally {
+            output.release()
+        }
+    }
+}