refactor: 清理 Electron 遗留代码并优化项目结构

- 删除 Electron 主进程代码 (src/main/)
- 删除构建产物文件夹 (build/, dist/, release/)
- 清理 package.json 中的 Electron 依赖和脚本
- 删除 TypeScript 配置中的 Electron 相关文件
- 优化前端代码结构至 Tauri 标准结构 (src/renderer → src/)
- 删除移动端图标和不必要文件
- 更新文档说明技术栈变更为 Tauri

src/App.css

@@ -0,0 +1,177 @@
+.app {
+  height: 100vh;
+  display: flex;
+  flex-direction: column;
+}
+
+.app-header {
+  background: #3498db;
+  color: white;
+  padding: 1rem 2rem;
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
+  /* 允许作为 Electron 的拖拽区域（macOS 隐藏标题栏时生效） */
+  -webkit-app-region: drag;
+  user-select: none;
+}
+
+.app-header h1 {
+  font-size: 1.5rem;
+  font-weight: 500;
+}
+
+.header-actions {
+  display: flex;
+  gap: 1rem;
+  /* header 内的交互元素需要排除拖拽，否则无法点击 */
+  -webkit-app-region: no-drag;
+}
+
+.refresh-btn, .add-btn {
+  padding: 0.5rem 1rem;
+  border: none;
+  border-radius: 4px;
+  cursor: pointer;
+  font-size: 0.9rem;
+  transition: all 0.2s;
+  /* 明确按钮不可拖拽，确保可点击 */
+  -webkit-app-region: no-drag;
+}
+
+.refresh-btn {
+  background: #3498db;
+  color: white;
+}
+
+.refresh-btn:hover:not(:disabled) {
+  background: #2980b9;
+}
+
+.refresh-btn:disabled {
+  opacity: 0.6;
+  cursor: not-allowed;
+}
+
+.import-btn {
+  background: rgba(255, 255, 255, 0.2);
+  color: white;
+  border: 1px solid rgba(255, 255, 255, 0.3);
+}
+
+.import-btn:hover {
+  background: rgba(255, 255, 255, 0.3);
+}
+
+.import-btn:focus {
+  outline: none;
+}
+
+.add-btn {
+  background: #27ae60;
+  color: white;
+  border: none;
+}
+
+.add-btn:hover {
+  background: #229954;
+}
+
+.add-btn:focus {
+  outline: none;
+}
+
+.app-main {
+  flex: 1;
+  padding: 2rem;
+  overflow-y: auto;
+}
+
+.config-path {
+  margin-top: 2rem;
+  padding: 1rem;
+  background: #ecf0f1;
+  border-radius: 4px;
+  font-size: 0.9rem;
+  color: #7f8c8d;
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+}
+
+.browse-btn {
+  padding: 0.5rem 1rem;
+  border: none;
+  border-radius: 4px;
+  background: #3498db;
+  color: white;
+  cursor: pointer;
+  font-size: 0.9rem;
+  transition: all 0.2s;
+  margin-left: 1rem;
+}
+
+.browse-btn:hover {
+  background: #2980b9;
+}
+
+/* 供应商列表区域 - 相对定位容器 */
+.provider-section {
+  position: relative;
+}
+
+/* 浮动通知 - 绝对定位，不占据空间 */
+.notification-floating {
+  position: absolute;
+  top: -10px;
+  left: 50%;
+  transform: translateX(-50%);
+  z-index: 100;
+  
+  padding: 0.75rem 1.25rem;
+  border-radius: 6px;
+  font-size: 0.9rem;
+  font-weight: 500;
+  
+  width: fit-content;
+  white-space: nowrap;
+}
+
+.fade-in {
+  animation: fadeIn 0.3s ease-out;
+}
+
+.fade-out {
+  animation: fadeOut 0.3s ease-out;
+}
+
+.notification-success {
+  background: linear-gradient(135deg, #27ae60 0%, #2ecc71 100%);
+  color: white;
+  box-shadow: 0 4px 12px rgba(39, 174, 96, 0.3);
+}
+
+.notification-error {
+  background: linear-gradient(135deg, #e74c3c 0%, #ec7063 100%);
+  color: white;
+  box-shadow: 0 4px 12px rgba(231, 76, 60, 0.3);
+}
+
+@keyframes fadeIn {
+  from {
+    opacity: 0;
+  }
+  to {
+    opacity: 1;
+  }
+}
+
+@keyframes fadeOut {
+  from {
+    opacity: 1;
+  }
+  to {
+    opacity: 0;
+  }
+}