feat(strm): 同名多版本择优 / keep_ext，并支持合并展示与播放切换 (#30)

* feat(strm): 同名多版本择优/keep_ext，并支持合并展示与播放切换

默认对同名不同扩展（如 .mkv/.mp4）按体积→mtime→扩展名优先级择优生成一条 strm，冲突打日志；开启 keep_ext 则分别生成 name.ext.strm。媒体详情与播放器可切换版本，列表继续合并同片多版本，Emby MediaSources 名称区分容器/分辨率。

Co-authored-by: truewhile <truewhile@users.noreply.github.com>

* fix(meta): 边车匹配忽略 .mkv.strm 中间扩展，同片共享 NFO/海报/字幕

NFO、海报、字幕与刮削写出统一使用 mediaSidecarBase 词干，使竞女01.mkv.strm
与竞女01.mp4.strm 配对同一套 竞女01.nfo / 竞女01-poster / 竞女01.srt；
仍兼容历史上的 name.mkv.nfo 命名。

Co-authored-by: truewhile <truewhile@users.noreply.github.com>

* fix(emby): People NFO 按共享词干匹配 keep_ext strm

resolveMediaPeople 改为查找竞女01.nfo（并兼容旧的竞女01.mkv.nfo），
同时修正把 decodeNFOFile 的 partial 误当 ok 导致完整 NFO 被跳过的问题。

Co-authored-by: truewhile <truewhile@users.noreply.github.com>

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Co-authored-by: Cursor Agent <cursoragent@cursor.com>
Co-authored-by: truewhile <truewhile@users.noreply.github.com>

internal/service/episode_parser.go

@@ -41,7 +41,10 @@ var (
 // ParseEpisode tries to extract (season, episode) from an arbitrary filename.
 // Returns (0, 0) when nothing recognisable is found.
 func ParseEpisode(path string) (season, episode int) {
-	name := strings.TrimSuffix(filepath.Base(path), filepath.Ext(path))
+	name := mediaSidecarBase(path)
+	if name == "" {
+		name = strings.TrimSuffix(filepath.Base(path), filepath.Ext(path))
+	}
 
 	if m := patSEnE.FindStringSubmatch(name); len(m) == 3 {
 		season = mustAtoi(m[1])
@@ -96,7 +99,10 @@ type episodeRef struct {
 }
 
 func episodeRefsFromTitle(path string) []episodeRef {
-	name := strings.TrimSuffix(filepath.Base(path), filepath.Ext(path))
+	name := mediaSidecarBase(path)
+	if name == "" {
+		name = strings.TrimSuffix(filepath.Base(path), filepath.Ext(path))
+	}
 	if refs := parseSEpisodeRange(name); len(refs) > 0 {
 		return refs
 	}