feat: add web entry to download desktop client

frontend/app.html

@@ -1796,6 +1796,10 @@
           {{ isLogin ? '还没有账号？' : '已有账号？' }}
           <a @click="toggleAuthMode">{{ isLogin ? '立即注册' : '去登录' }}</a>
         </div>
+        <button type="button" class="btn btn-secondary" style="margin-top: 12px;" :disabled="desktopClientDownloading" @click="downloadDesktopClient">
+          <i :class="desktopClientDownloading ? 'fas fa-spinner fa-spin' : 'fas fa-desktop'"></i>
+          {{ desktopClientDownloading ? '获取安装包...' : '下载桌面客户端' }}
+        </button>
       </div>
     </div>
     <!-- 导航栏 -->
@@ -1818,6 +1822,10 @@
 
           <i class="fas fa-cog"></i> 设置
         </div>
+        <button class="btn btn-secondary" :disabled="desktopClientDownloading" @click="downloadDesktopClient">
+          <i :class="desktopClientDownloading ? 'fas fa-spinner fa-spin' : 'fas fa-download'"></i>
+          {{ desktopClientDownloading ? '准备中...' : '下载客户端' }}
+        </button>
         <div class="user-info">
           <i class="fas fa-user-circle"></i>
           <span>{{ user.username }}</span>
@@ -2480,6 +2488,21 @@
           <p class="settings-page-subtitle">管理存储策略、主题外观与账号安全</p>
         </div>
 
+        <h3 class="settings-section-title" style="margin-bottom: 20px;">
+          <i class="fas fa-desktop"></i> 客户端下载
+        </h3>
+        <div class="settings-panel" style="background: var(--bg-card); padding: 20px; border-radius: 12px; border: 1px solid var(--glass-border); margin-bottom: 30px;">
+          <div style="display: flex; justify-content: space-between; align-items: center; gap: 12px; flex-wrap: wrap;">
+            <div style="color: var(--text-secondary); font-size: 13px;">
+              下载最新版桌面客户端（Windows x64）
+            </div>
+            <button class="btn btn-primary" :disabled="desktopClientDownloading" @click="downloadDesktopClient">
+              <i :class="desktopClientDownloading ? 'fas fa-spinner fa-spin' : 'fas fa-download'"></i>
+              {{ desktopClientDownloading ? '获取安装包...' : '下载桌面客户端' }}
+            </button>
+          </div>
+        </div>
+
         <!-- 存储管理 - 仅用户可选择 -->
         <div v-if="user && !user.is_admin && storagePermission === 'user_choice'" class="settings-section settings-storage-choice" style="margin-bottom: 40px;">
           <h3 class="settings-section-title" style="margin-bottom: 20px;">

frontend/app.js

@@ -271,6 +271,8 @@ createApp({
         error: '',
         lastLoadedAt: ''
       },
+      desktopClientDownloading: false,
+      desktopClientDownloadUrl: '',
 
       // 健康检测
       healthCheck: {
@@ -731,6 +733,70 @@ createApp({
       this._debouncedLoadUserProfile();
     },
 
+    resolveDesktopClientUrl(rawUrl) {
+      const trimmed = String(rawUrl || '').trim();
+      if (!trimmed) return '';
+      try {
+        return new URL(trimmed, `${this.apiBase}/`).toString();
+      } catch (error) {
+        console.warn('[客户端下载] 下载地址格式异常:', trimmed, error);
+        return '';
+      }
+    },
+
+    triggerDesktopClientDownload(url) {
+      const resolved = this.resolveDesktopClientUrl(url);
+      if (!resolved) return false;
+      const link = document.createElement('a');
+      link.href = resolved;
+      link.target = '_blank';
+      link.rel = 'noopener noreferrer';
+      link.download = '';
+      document.body.appendChild(link);
+      link.click();
+      link.remove();
+      return true;
+    },
+
+    async fetchDesktopClientDownloadUrl() {
+      try {
+        const response = await axios.get(`${this.apiBase}/api/client/desktop-update`, {
+          params: {
+            currentVersion: '0.0.0',
+            platform: 'windows-x64',
+            channel: 'stable'
+          }
+        });
+        const resolved = this.resolveDesktopClientUrl(response.data?.downloadUrl);
+        if (resolved) {
+          this.desktopClientDownloadUrl = resolved;
+          return resolved;
+        }
+      } catch (error) {
+        console.warn('[客户端下载] 获取最新版下载地址失败:', error?.message || error);
+      }
+      return this.resolveDesktopClientUrl(this.desktopClientDownloadUrl);
+    },
+
+    async downloadDesktopClient() {
+      if (this.desktopClientDownloading) return;
+      this.desktopClientDownloading = true;
+      try {
+        const downloadUrl = await this.fetchDesktopClientDownloadUrl();
+        if (!downloadUrl) {
+          this.showToast('warning', '暂无安装包', '服务器尚未配置客户端安装包下载地址');
+          return;
+        }
+        if (!this.triggerDesktopClientDownload(downloadUrl)) {
+          this.showToast('error', '下载失败', '下载地址无效，请稍后重试');
+          return;
+        }
+        this.showToast('success', '开始下载', '客户端安装包已开始下载');
+      } finally {
+        this.desktopClientDownloading = false;
+      }
+    },
+
     // ========== 主题管理 ==========
     // 初始化主题
     async initTheme() {