fix: ComputeAssetHashes 并发安全 + theme 页重复加载 JS 导致双写 panic

- helper.go: 用 sync.RWMutex 保护 assetHashes，构建本地 map 后原子替换
- theme.html: 删除硬编码 script 标签（footer ExtraJS 已加载），
  修复 site-settings-theme.js 执行两次 → applyTheme 触发两次 → 并发写 map panic

internal/common/helper.go

@@ -11,6 +11,7 @@ import (
 	"path/filepath"
 	"regexp"
 	"strconv"
+	"sync"
 	"time"
 
 	"metazone.cc/mce/internal/model"
@@ -19,22 +20,31 @@ import (
 )
 
 // assetHashes 静态资源文件哈希表（URL 路径 → 短哈希，文件不变哈希不变）
-var assetHashes map[string]string
+var (
+	assetHashes map[string]string
+	assetMu     sync.RWMutex
+)
 
 // ComputeAssetHashes 遍历 static 目录，计算每个文件的 CRC32 作为版本号
+// 构建本地 map 后原子替换，避免并发读写冲突
 func ComputeAssetHashes(templateDir string) {
-	assetHashes = make(map[string]string)
+	mu := make(map[string]string)
 	// 前端主题：templates/MetaLab-2026/static → URL /static/
-	walkStaticDir(filepath.Join(templateDir, "static"), "/static")
+	walkStaticDirInto(mu, filepath.Join(templateDir, "static"), "/static")
 	// 共享资源：templates/shared/static → URL /shared/static/
-	walkStaticDir(filepath.Join(filepath.Dir(templateDir), "shared", "static"), "/shared/static")
+	walkStaticDirInto(mu, filepath.Join(filepath.Dir(templateDir), "shared", "static"), "/shared/static")
 	// 管理后台：templates/admin/static → URL /admin/static/
-	walkStaticDir(filepath.Join(filepath.Dir(templateDir), "admin", "static"), "/admin/static")
-	log.Printf("[AssetHashes] computed %d file hashes", len(assetHashes))
+	walkStaticDirInto(mu, filepath.Join(filepath.Dir(templateDir), "admin", "static"), "/admin/static")
+
+	assetMu.Lock()
+	assetHashes = mu
+	assetMu.Unlock()
+
+	log.Printf("[AssetHashes] computed %d file hashes", len(mu))
 }
 
-// walkStaticDir 遍历目录，计算每个 .js/.css 的 CRC32，存入 assetHashes
-func walkStaticDir(dir, urlPrefix string) {
+// walkStaticDirInto 遍历目录，计算每个 .js/.css 的 CRC32，存入目标 map
+func walkStaticDirInto(dst map[string]string, dir, urlPrefix string) {
 	_ = filepath.WalkDir(dir, func(path string, d fs.DirEntry, err error) error {
 		if err != nil || d.IsDir() {
 			return nil
@@ -52,14 +62,17 @@ func walkStaticDir(dir, urlPrefix string) {
 		// 生成 URL 路径：urlPrefix + 相对于 dir 的子路径
 		rel, _ := filepath.Rel(dir, path)
 		urlPath := urlPrefix + "/" + filepath.ToSlash(rel)
-		assetHashes[urlPath] = shortHash
+		dst[urlPath] = shortHash
 		return nil
 	})
 }
 
-// AssetV 返回指定静态资源的哈希版本号（模板函数）
+// AssetV 返回指定静态资源的哈希版本号（模板函数，并发安全）
 func AssetV(path string) string {
-	if h, ok := assetHashes[path]; ok {
+	assetMu.RLock()
+	h, ok := assetHashes[path]
+	assetMu.RUnlock()
+	if ok {
 		return h
 	}
 	return "0"

templates/admin/html/site-settings/theme.html

@@ -41,4 +41,3 @@
             </div>
         </div>
 {{template "admin/layout/footer.html" .}}
-<script src="/admin/static/js/site-settings-theme.js?v={{assetV "/admin/static/js/site-settings-theme.js"}}" nonce="{{.CSPNonce}}"></script>