fix(mobile): close the full screen player when playback ends

When TTS finished or failed while the full screen player was open, the
player rendered nothing but its transparent modal stayed in place. The
app underneath was visible but did not take touches, and iOS had no
gesture to leave. The screen now dismisses itself once nothing is
playing.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/mobile/src/screens/PlayerScreen.tsx

@@ -1,6 +1,6 @@
 import { cn } from "@follow/utils"
 import { LinearGradient } from "expo-linear-gradient"
-import { useEffect, useMemo } from "react"
+import { use, useEffect, useMemo } from "react"
 import { StyleSheet, View } from "react-native"
 import Reanimated, {
   cancelAnimation,
@@ -14,6 +14,7 @@ import { SheetScreen } from "react-native-sheet-transitions"
 import { Image } from "@/src/components/ui/image/Image"
 import { Text } from "@/src/components/ui/typography/Text"
 import { useNavigation } from "@/src/lib/navigation/hooks"
+import { ScreenItemContext } from "@/src/lib/navigation/ScreenItemContext"
 
 import { gentleSpringPreset } from "../constants/spring"
 import type { NavigationControllerView } from "../lib/navigation/types"
@@ -68,6 +69,15 @@ export const PlayerScreen: NavigationControllerView = () => {
     [isGradientLight],
   )
   const navigation = useNavigation()
+  // Once playback ends there is nothing to show, and the empty transparent modal would keep
+  // covering the app. The delay rides out the gap between two tracks.
+  const hasActivePlayable = !!activePlayable
+  const { screenId } = use(ScreenItemContext)
+  useEffect(() => {
+    if (hasActivePlayable) return
+    const timer = setTimeout(() => navigation.__internal_dismiss(screenId), 300)
+    return () => clearTimeout(timer)
+  }, [hasActivePlayable, navigation, screenId])
   if (!activePlayable) {
     return null
   }