feat(backend): book list/detail/delete with embedded progress + cache cleanup

backend/internal/config/config.go

@@ -3,6 +3,7 @@ package config
 import (
 	"fmt"
 	"os"
+	"path/filepath"
 	"strconv"
 	"time"
 )
@@ -39,6 +40,14 @@ func Load() (*Config, error) {
 	if secret == "" {
 		return nil, fmt.Errorf("JWT_SECRET required")
 	}
+	// resolveDir: macOS 开发机上 /var、/tmp 是指向 /private 的软链,
+	// 启动时解析一次才能让 root_path 前缀校验对上真实路径;目录不存在/出错则保留原值(Docker 路径不受影响)
+	resolveDir := func(dir string) string {
+		if r, e := filepath.EvalSymlinks(dir); e == nil {
+			return r
+		}
+		return dir
+	}
 	return &Config{
 		Addr:          env("ADDR", ":8080"),
 		DatabaseURL:   env("DATABASE_URL", ""),
@@ -46,8 +55,8 @@ func Load() (*Config, error) {
 		JWTSecret:     []byte(secret),
 		AdminUser:     env("ADMIN_USER", ""),
 		AdminPassword: env("ADMIN_PASSWORD", ""),
-		BooksDir:      env("BOOKS_DIR", "/data/books"),
-		CacheDir:      env("CACHE_DIR", "/data/cache"),
+		BooksDir:      resolveDir(env("BOOKS_DIR", "/data/books")),
+		CacheDir:      resolveDir(env("CACHE_DIR", "/data/cache")),
 		ScanInterval:  time.Duration(scanSec) * time.Second,
 		UploadMaxMB:   uploadMB,
 	}, nil