✨ 前端添加HTML实体解码兜底

- 添加decodeHtmlEntities方法解码文件名
- 添加getFileDisplayName统一获取显示名称
- 确保文件名正确显示，即使后端未解码

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

frontend/app.js

@@ -2015,6 +2015,48 @@ handleDragLeave(e) {
       return d.toLocaleString();
     },
 
+    // HTML实体解码（前端兜底，防止已实体化的文件名显示乱码）
+    decodeHtmlEntities(str) {
+      if (typeof str !== 'string') return str;
+      const entityMap = {
+        amp: '&',
+        lt: '<',
+        gt: '>',
+        quot: '"',
+        apos: "'",
+        '#x27': "'",
+        '#x2F': '/',
+        '#x60': '`'
+      };
+      const decodeOnce = (input) =>
+        input.replace(/&(#x[0-9a-fA-F]+|#\d+|[a-zA-Z]+);/g, (match, code) => {
+          if (code[0] === '#') {
+            const isHex = code[1]?.toLowerCase() === 'x';
+            const num = isHex ? parseInt(code.slice(2), 16) : parseInt(code.slice(1), 10);
+            if (!Number.isNaN(num)) {
+              return String.fromCharCode(num);
+            }
+            return match;
+          }
+          const mapped = entityMap[code];
+          return mapped !== undefined ? mapped : match;
+        });
+      let output = str;
+      let decoded = decodeOnce(output);
+      while (decoded !== output) {
+        output = decoded;
+        decoded = decodeOnce(output);
+      }
+      return output;
+    },
+
+    getFileDisplayName(file) {
+      if (!file) return '';
+      const base = file.displayName || file.name || '';
+      const decoded = this.decodeHtmlEntities(base);
+      return decoded || base;
+    },
+
     openShare(url) {
       if (!url) return;
       const newWindow = window.open(url, '_blank', 'noopener');