refactor: 主题切换移到⚙️设置下拉菜单

- 移除标题栏独立主题按钮(🌙/☀️)
- 新增⚙️设置按钮 → 下拉菜单
- 菜单项: 「☀️ 亮色主题」/「🌙 暗色主题」动态文字
- 点击菜单外自动关闭
- 菜单样式: bg-slate-800, rounded, shadow, 最小宽度200px

web/app/files.html

@@ -70,12 +70,20 @@
       <!-- Tabs (clickable, not draggable) -->
       <div id="editorTabBar" class="flex flex-1 overflow-x-auto min-w-0"></div>
       <!-- Right buttons -->
-      <div class="flex items-center shrink-0">
-        <button onclick="toggleEditorTheme()" id="themeBtn" class="text-slate-500 hover:text-white px-2 py-2 text-sm hover:bg-slate-700" title="切换亮色/暗色主题">🌙</button>
+      <div class="flex items-center shrink-0 relative">
+        <!-- Settings menu -->
+        <button onclick="toggleEditorMenu(event)" class="text-slate-500 hover:text-white px-2 py-2 text-sm hover:bg-slate-700" title="设置">⚙️</button>
         <button onclick="toggleEditorSize()" id="sizeBtn" class="text-slate-500 hover:text-white px-2 py-2 text-sm hover:bg-slate-700" title="最大化/还原">⬜</button>
         <button onclick="toggleEditorFullscreen()" id="fsBtn" class="text-slate-500 hover:text-white px-2 py-2 text-sm hover:bg-slate-700" title="全屏">⤢</button>
         <button onclick="minimizeEditor()" class="text-slate-500 hover:text-white px-2 py-2 text-sm hover:bg-slate-700" title="最小化">—</button>
         <button onclick="closeAllTabs()" class="text-slate-500 hover:text-red-400 px-2 py-2 text-sm hover:bg-red-900/30" title="关闭全部">✕</button>
+        <!-- Settings dropdown menu -->
+        <div id="editorMenu" class="hidden absolute right-0 top-full mt-1 bg-slate-800 border border-slate-700 rounded-lg shadow-xl py-2 min-w-[200px] z-50">
+          <div class="px-4 py-2 text-xs text-slate-500 font-medium border-b border-slate-700 mb-1">编辑器设置</div>
+          <button onclick="toggleEditorTheme()" class="w-full text-left px-4 py-2 text-sm text-slate-200 hover:bg-slate-700 flex items-center gap-2">
+            <span id="themeIcon">☀️</span> <span id="themeLabel">亮色主题</span>
+          </button>
+        </div>
       </div>
     </div>
     <!-- Body: file tree + editor -->
@@ -650,8 +658,21 @@
     loadEditorTheme();
 
     function updateThemeBtn(){
-      const btn=document.getElementById('themeBtn');
-      if(btn)btn.textContent=_editorTheme==='vs-dark'?'🌙':'☀️';
+      const icon=document.getElementById('themeIcon');
+      const label=document.getElementById('themeLabel');
+      if(icon)icon.textContent=_editorTheme==='vs-dark'?'🌙':'☀️';
+      if(label)label.textContent=_editorTheme==='vs-dark'?'暗色主题':'亮色主题';
+    }
+
+    function toggleEditorMenu(e){
+      e.stopPropagation();
+      const menu=document.getElementById('editorMenu');
+      menu.classList.toggle('hidden');
+      // Close on outside click
+      if(!menu.classList.contains('hidden')){
+        const close=()=>{menu.classList.add('hidden');document.removeEventListener('click',close)};
+        setTimeout(()=>document.addEventListener('click',close),10);
+      }
     }
 
     function toggleEditorTheme(){
@@ -659,6 +680,7 @@
       _openTabs.forEach(t=>{if(t.editor)t.editor.updateOptions({theme:_editorTheme})});
       updateThemeBtn();
       apiFetch(API+'/settings/editor_theme',{method:'PUT',headers:apiHeadersJSON(),body:JSON.stringify({value:_editorTheme})});
+      document.getElementById('editorMenu').classList.add('hidden');
     }
 
     function openFileInEditor(path,name,content){