fixed some bugs on ios

ios/OralTrainer/Player/PlayerController.swift

@@ -318,21 +318,27 @@ final class PlayerController: ObservableObject {
     }
 
     /// 只播放当前句子，播完自动暂停并回到句首（评测“播放原句”）。
+    /// 必须先打上句尾标记再 seek，这样 completion 里的 forwardPlaybackEndTime
+    /// 会卡在当前句 endMs，而不是等 250ms 观察器才停。
     func playCurrentSentenceAndStop() {
         guard let sentence = currentSentence else {
             return
         }
-        performSeek(to: sentenceSeekPosition(sentence))
         stopAtSentenceEnd = true
         stopAtSentenceEndIndex = sentence.index
-        play()
+        lastSentenceIndex = sentence.index
+        playbackIntent = true
+        performSeek(to: sentenceSeekPosition(sentence), resumePlayback: true)
     }
 
     // MARK: - 设置
 
     func setContinuousPlayback(_ enabled: Bool) {
         config.continuousPlayback = enabled
-        refreshSentenceBoundaryGuard()
+        if !enabled {
+            lastSentenceIndex = currentSentence?.index ?? lastSentenceIndex
+        }
+        refreshSentenceBoundaryGuard(force: true)
     }
 
     func setSentenceMode(_ enabled: Bool) {
@@ -783,6 +789,13 @@ final class PlayerController: ObservableObject {
             tick()
             return
         }
+        // 评测“播放原句”即使处于连续播放，也要用当前句硬边界，不能滑进下一句。
+        if stopAtSentenceEnd,
+           let index = stopAtSentenceEndIndex,
+           let sentence = mediaItem?.sentences.first(where: { $0.index == index }) {
+            applySentenceEndAction(sentence)
+            return
+        }
         // 若最后一个句子的 endMs 就是视频末尾，forwardPlaybackEndTime 和自然结束
         // 是同一时间点。此时必须执行“当前句”的句尾动作，而不能整条视频回零。
         if config.sentenceMode,