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>

---------

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

internal/service/media_versions_test.go

@@ -1,6 +1,7 @@
 package service
 
 import (
+	"strings"
 	"testing"
 	"time"
 
@@ -264,3 +265,43 @@ func TestGroupMediaVersionsDoesNotMergeAcrossDifferentLibrariesForMovies(t *test
 		t.Fatalf("expected 2 separate groups for movies in different libraries, got %d", len(grouped))
 	}
 }
+
+func TestGroupMediaVersionsMergesKeepExtStrmVariants(t *testing.T) {
+	mkv := model.Media{
+		LibraryID: "movies",
+		Title:     "竞女01",
+		Path:      "/strm/竞女01.mkv.strm",
+		SizeBytes: 500,
+		STRMURL:   "/api/strm/play/cloud115/video.mkv?pickcode=a",
+	}
+	mp4 := model.Media{
+		LibraryID: "movies",
+		Title:     "竞女01",
+		Path:      "/strm/竞女01.mp4.strm",
+		SizeBytes: 100,
+		STRMURL:   "/api/strm/play/cloud115/video.mp4?pickcode=b",
+	}
+	grouped := groupMediaVersions([]model.Media{mkv, mp4})
+	if len(grouped) != 1 {
+		t.Fatalf("grouped len = %d, want 1", len(grouped))
+	}
+	if len(grouped[0].Versions) != 2 {
+		t.Fatalf("versions len = %d, want 2", len(grouped[0].Versions))
+	}
+	if grouped[0].Path != mkv.Path {
+		t.Fatalf("primary should be larger mkv, got %q", grouped[0].Path)
+	}
+}
+
+func TestMediaVersionLabelUsesContainerAndSize(t *testing.T) {
+	label := MediaVersionLabel(model.Media{
+		Title:     "竞女01",
+		Path:      "/strm/竞女01.mkv.strm",
+		Height:    1080,
+		SizeBytes: 1024 * 1024 * 1200,
+		STRMURL:   "/api/strm/play/cloud115/video.mkv?pickcode=a",
+	})
+	if !strings.Contains(label, "1080p") || !strings.Contains(strings.ToUpper(label), "MKV") {
+		t.Fatalf("unexpected label %q", label)
+	}
+}