同步上游 zip：合并任务后台化 + 合并整剧可直接播放；保留 ultrafast+4线程 转码优化与 .gitignore 本地规则

internal/app/ui_playback_merged.go

@@ -0,0 +1,30 @@
+package app
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"strings"
+)
+
+const mergedPlaybackPrefix = "merged:"
+
+func (app *UIApp) mergedPlaybackTaskLocked(id string) (Task, string, error) {
+	dramaID, ok := strings.CutPrefix(id, mergedPlaybackPrefix)
+	if !ok || dramaID == "" {
+		return Task{}, "", errors.New("合并播放记录无效")
+	}
+	state := app.merges[dramaID]
+	if state == nil || state.Status != "success" {
+		return Task{}, "", errors.New("本剧尚无合并成功的文件")
+	}
+	path := completedPlaybackPath(&UITask{Status: uiStatusSuccess, Path: state.OutputPath})
+	if path == "" {
+		return Task{}, "", errors.New("本地合并文件不存在或已移动，请重新合并")
+	}
+	label := fmt.Sprintf("全集（第%d–%d集）", state.StartEpisode, state.EndEpisode)
+	episode, _ := json.Marshal(label)
+	task := Task{DramaID: dramaID, DramaTitle: state.DramaTitle, Index: 1, Total: 1, OutPath: path,
+		Chapter: Chapter{ID: fmt.Sprintf("%s:%d-%d", id, state.StartEpisode, state.EndEpisode), Source: sourceFromDramaID(dramaID), Title: label, CurrentEpisode: episode}}
+	return task, path, nil
+}