refactor: 按模块重构项目结构

- 删除 vars 全局状态，按职责拆分 internal/ 包：scanner/probe/classify/organize/mover/store/digest
- 数据驱动归类规则替代图片/视频重复分支，store 改为结构体实例
- build.sh 按系统类型编译：Windows 用 upx 压缩，macOS/Linux 不压缩
- 忽略目录拆分：图片_已忽略 / 视频_已忽略
- 输出构建产物加入 .gitignore

internal/scanner/scanner.go

@@ -0,0 +1,138 @@
+// Package scanner 负责递归扫描文件、读取 MIME 并按类型过滤。
+package scanner
+
+import (
+	"fmt"
+	"os"
+	"path"
+	"path/filepath"
+	"strings"
+
+	"kenaito-media-picker/internal/probe"
+
+	"github.com/gabriel-vasile/mimetype"
+	"github.com/redmask-hb/GoSimplePrint/goPrint"
+)
+
+// File 扫描到的文件信息
+type File struct {
+	Path string // 完整路径
+	Name string // 文件名（含扩展名）
+	Ext  string // 扩展名（含点）
+	Mime string // MIME 类型
+}
+
+// Result 过滤结果
+type Result struct {
+	Files  []File // 全部文件
+	Images []File // 图片文件
+	Media  []File // 待 ffprobe 确认的媒体候选
+}
+
+// Options 扫描选项
+type Options struct {
+	RootDir   string   // 扫描根目录
+	SkipDir   string   // 白名单输出目录，整目录跳过
+	SkipNames []string // 按文件名跳过（数据库、ffprobe 等）
+}
+
+// Scan 递归扫描目录并读取每个文件的 MIME 信息
+func Scan(opts Options) (*Result, error) {
+	res := &Result{}
+	err := filepath.Walk(opts.RootDir, func(currentPath string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if info.IsDir() {
+			if opts.SkipDir != "" && currentPath == opts.SkipDir {
+				return filepath.SkipDir
+			}
+			return nil
+		}
+		for _, n := range opts.SkipNames {
+			if info.Name() == n {
+				return nil
+			}
+		}
+		res.Files = append(res.Files, File{
+			Path: currentPath,
+			Name: info.Name(),
+			Ext:  path.Ext(currentPath),
+		})
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	total := len(res.Files)
+	fmt.Printf("=== 文件总数: %d \n", total)
+	bar := goPrint.NewBar(100)
+	bar.SetNotice("=== 扫描文件Mime：")
+	bar.SetGraph(">")
+	bar.SetNoticeColor(goPrint.FontColor.Red)
+	for i := range res.Files {
+		res.Files[i].Mime = detectMime(res.Files[i].Path)
+		bar.PrintBar(percent(i+1, total))
+	}
+	bar.PrintEnd("=== Finish")
+	return res, nil
+}
+
+// Filter 将文件分为图片与媒体候选
+func (r *Result) Filter() {
+	for _, f := range r.Files {
+		if strings.Contains(f.Mime, "image/") || probe.IsSupportImage(f.Ext) || strings.EqualFold(f.Ext, ".psd") {
+			r.Images = append(r.Images, f)
+			continue
+		}
+		if isPotentialMedia(f.Mime) {
+			r.Media = append(r.Media, f)
+			continue
+		}
+		// 明显的非媒体文件（代码/文档/压缩包等）直接不处理
+	}
+}
+
+// detectMime 读取文件的 MIME 类型
+func detectMime(filePath string) string {
+	mt, err := mimetype.DetectFile(filePath)
+	if err != nil {
+		return ""
+	}
+	return mt.String()
+}
+
+// isPotentialMedia 判断是否可能是媒体文件（交由 ffprobe 进一步确认）
+func isPotentialMedia(fileMime string) bool {
+	if fileMime == "" || fileMime == "application/octet-stream" {
+		return true
+	}
+	if strings.HasPrefix(fileMime, "text/") {
+		return false
+	}
+	if strings.HasPrefix(fileMime, "video/") || strings.HasPrefix(fileMime, "audio/") || strings.HasPrefix(fileMime, "image/") {
+		return true
+	}
+	switch fileMime {
+	case "application/zip", "application/gzip", "application/x-gzip", "application/pdf",
+		"application/json", "application/xml", "application/x-httpd-php", "application/x-sh",
+		"application/javascript", "application/x-7z-compressed", "application/x-rar-compressed",
+		"application/x-tar", "application/x-bzip2", "application/x-archive", "application/vnd.sqlite3",
+		"application/vnd.microsoft.portable-executable", "application/x-dosexec", "application/x-executable",
+		"application/vnd.openxmlformats-officedocument.wordprocessingml.document",
+		"application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
+		"application/vnd.openxmlformats-officedocument.presentationml.presentation",
+		"application/msword", "application/vnd.ms-excel", "application/vnd.ms-powerpoint":
+		return false
+	}
+	return true
+}
+
+// percent 计算百分比（0~100），total 为 0 时返回 100
+func percent(part, total int) int {
+	if total <= 0 {
+		return 100
+	}
+	return int(float64(part) / float64(total) * 100)
+}