feat: add loading screen with fade-out animation

Implement a loading screen that displays while page loads and gracefully fades out after 1.5 seconds. Includes CSS animations and proper cleanup to prevent interaction blocking.

style.css

@@ -1,3 +1,40 @@
+/* --- 加载屏幕 --- */
+#loading-screen {
+    position: fixed;
+    top: 0;
+    left: 0;
+    width: 100%;
+    height: 100%;
+    background-color: #1a1a1a;
+    display: flex;
+    justify-content: center;
+    align-items: center;
+    z-index: 100;
+    transition: opacity 0.5s ease-out;
+}
+
+#loading-screen img {
+    width: 150px; /* 或者您希望的任何尺寸 */
+    height: auto;
+    animation: pulse-loader 2s infinite;
+}
+
+@keyframes pulse-loader {
+    0% {
+        transform: scale(1);
+        opacity: 0.8;
+    }
+    50% {
+        transform: scale(1.1);
+        opacity: 1;
+    }
+    100% {
+        transform: scale(1);
+        opacity: 0.8;
+    }
+}
+
+
 /* --- 基本重置和全局样式 --- */
 * {
     margin: 0;