新增: 相册展示模块（左侧幻灯片+进度条+目录选择）

- 左侧固定卡片展示照片幻灯片，淡入淡出切换
- 进度条动画显示当前照片剩余时间
- 设置窗口支持选择图片目录和切换间隔(5/10/15/20/30/60秒)
- Win32 SHBrowseForFolderW 目录选择对话框
- Go 端管理幻灯片状态，按间隔推送照片 data URI

web/settings.html

@@ -330,6 +330,31 @@ input[type="text"]:focus { border-color: var(--input-border-focus); }
   </div>
 </div>
 
+<!-- 相册 -->
+<div class="section">
+  <div class="section-label">相册</div>
+  <div class="card">
+    <div class="item">
+      <div class="item-desc" id="photoDirDisplay">未选择目录</div>
+      <div class="btn-group">
+        <button class="btn" id="btnPickPhotoDir">选择目录</button>
+        <button class="btn btn-sm" id="btnClearPhotoDir" style="display:none">清除</button>
+      </div>
+    </div>
+    <div class="item">
+      <div class="item-label">切换间隔</div>
+      <select id="photoInterval">
+        <option value="5">5 秒</option>
+        <option value="10">10 秒</option>
+        <option value="15" selected>15 秒</option>
+        <option value="20">20 秒</option>
+        <option value="30">30 秒</option>
+        <option value="60">60 秒</option>
+      </select>
+    </div>
+  </div>
+</div>
+
 <!-- 星座 + 城市 -->
 <div class="section">
   <div class="section-label">个性化</div>
@@ -462,6 +487,26 @@ document.getElementById('themeSelect').addEventListener('change', function() {
   document.getElementById('textInputRow').style.display = this.value === 'text' ? 'flex' : 'none';
 });
 
+document.getElementById('btnPickPhotoDir').addEventListener('click', function() {
+  if (!window.pickPhotoDir) return;
+  window.pickPhotoDir().then(function(dir) {
+    if (dir) {
+      document.getElementById('photoDirDisplay').textContent = dir;
+      document.getElementById('btnClearPhotoDir').style.display = '';
+    }
+  });
+});
+document.getElementById('btnClearPhotoDir').addEventListener('click', function() {
+  if (!window.clearPhotoDir) return;
+  window.clearPhotoDir().then(function() {
+    document.getElementById('photoDirDisplay').textContent = '未选择目录';
+    document.getElementById('btnClearPhotoDir').style.display = 'none';
+  });
+});
+document.getElementById('photoInterval').addEventListener('change', function() {
+  if (window.savePhotoInterval) window.savePhotoInterval(parseInt(this.value));
+});
+
 var textTimer = null;
 document.getElementById('wallpaperText').addEventListener('input', function() {
   clearTimeout(textTimer);
@@ -672,6 +717,12 @@ if (window.loadAllSettings) {
     if (s.knowledgeKeyword) document.getElementById('knowledgeKeyword').value = s.knowledgeKeyword;
     if (s.knowledgePrompt) document.getElementById('knowledgePrompt').value = s.knowledgePrompt;
     if (s.theme === 'text') document.getElementById('textInputRow').style.display = 'flex';
+    // Photo state
+    if (s.photoDir) {
+      document.getElementById('photoDirDisplay').textContent = s.photoDir;
+      document.getElementById('btnClearPhotoDir').style.display = '';
+    }
+    if (s.photoInterval) document.getElementById('photoInterval').value = s.photoInterval;
     // Color state
     if (s.color1) { currentColor1 = s.color1; currentColor2 = s.color2 || ''; currentGradient = s.colorGradient || false; }
     if (s.wallpaperType === 'color') updateColorPreview();