fix(android,ios): the player names the episode, not its file

The header under the episode's numbering showed `Episode::detail`, which
falls back to the file name — `[Judas] Chainsaw Man - S01E01.mkv` on a
phone, where the desktop shows `Dog & Chainsaw`. It now shows the
provider's name for the episode, else the one the file name gave it, and
nothing rather than the file name: the release group's tag is no caption,
and it is what a screenshot of the player would carry away.

android/app/src/main/java/io/narl/protonstream/playback/PlayerScreen.kt

@@ -97,6 +97,7 @@ import androidx.core.view.WindowInsetsCompat
 import androidx.core.view.WindowInsetsControllerCompat
 import io.narl.protonstream.settings.SettingsStore
 import io.narl.protonstream.native.NativeRuntime
+import io.narl.protonstream.ui.shownName
 import io.narl.protonstream.ui.theme.AccentButton
 import io.narl.protonstream.ui.theme.AccentTrack
 import io.narl.protonstream.ui.theme.EdgedButton
@@ -567,8 +568,11 @@ fun PlayerScreen(
                         overflow = TextOverflow.Ellipsis,
                         style = MaterialTheme.typography.titleMedium,
                     )
+                    // The episode's name, never its file name: a release
+                    // group's tag is no caption, and it is what a screenshot
+                    // of the player would carry away.
                     Text(
-                        listOfNotNull(title.displayName, episode.detail.takeIf(String::isNotBlank))
+                        listOfNotNull(title.displayName, episode.shownName())
                             .joinToString("  •  "),
                         color = Color.White.copy(alpha = 0.7f),
                         maxLines = 1,

android/app/src/main/java/io/narl/protonstream/ui/Common.kt

@@ -221,6 +221,13 @@ internal fun rememberQueueReason(key: Any?): String? {
     }
 }
 
+/**
+ * The episode's own name: the provider's, else the one the filename gave it.
+ * `null` rather than the filename, which is a release group's tag and the
+ * episode's numbering again.
+ */
+internal fun EpisodeRecord.shownName(): String? = providerName ?: detail.takeIf { it != name && it.isNotBlank() }
+
 /**
  * What an episode row is headed with: "1. Mother and Children".
  *
@@ -229,7 +236,7 @@ internal fun rememberQueueReason(key: Any?): String? {
  * of `[Group] Show - S01E01.mkv` is forty rows that differ in two characters.
  */
 internal fun EpisodeRecord.heading(position: Int): String {
-    val named = providerName ?: detail.takeIf { it != name }
+    val named = shownName()
     val number = number?.toInt()
     return when {
         named != null && number != null -> "$number. $named"

android/app/src/test/java/io/narl/protonstream/ui/EpisodeNameTest.kt

@@ -0,0 +1,24 @@
+package io.narl.protonstream.ui
+
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNull
+import org.junit.Test
+import uniffi.pstr_android.EpisodeRecord
+
+class EpisodeNameTest {
+    private fun episode(name: String, detail: String, providerName: String? = null) = EpisodeRecord(
+        shareId = "s", volumeId = "v", linkId = "l", name = name, label = "S01E01", detail = detail,
+        season = 1u, number = 1u, size = null, progress = null, resumeAt = null,
+        watched = false, offline = false, providerName = providerName, providerOverview = null, stillUrl = null,
+        airDate = null, lastPlayed = 0,
+    )
+
+    @Test
+    fun `the player captions an episode with its name and never its filename`() {
+        val file = "[Group] Show - S01E01.mkv"
+        assertEquals("Dog & Chainsaw", episode(file, file, providerName = "Dog & Chainsaw").shownName())
+        assertEquals("Winter Is Coming", episode(file, "Winter Is Coming").shownName())
+        assertNull(episode(file, file).shownName())
+        assertNull(episode(file, "").shownName())
+    }
+}