Remove music player and related context/hooks

Deleted the audio player component, songs context, and use-music hook, along with all related code and configuration. Updated affected components and pages to remove music player dependencies and UI. Also improved sidebar, background, and about page UI, and refactored site config icons to use react-icons.

packages/napcat-webui-frontend/src/styles/globals.css

@@ -6,15 +6,45 @@
 
 body {
   font-family:
-    'Aa偷吃可爱长大的',
-    PingFang SC,
-    Helvetica Neue,
-    Microsoft YaHei,
+    'Quicksand',
+    'Nunito',
+    'Inter',
+    -apple-system,
+    BlinkMacSystemFont,
+    'Segoe UI',
+    Roboto,
+    'Helvetica Neue',
+    Arial,
+    'PingFang SC',
+    'Microsoft YaHei',
     sans-serif !important;
     -webkit-font-smoothing: antialiased;
     -moz-osx-font-smoothing: grayscale;
     text-rendering: optimizeLegibility;
     font-smooth: always;
+    letter-spacing: 0.02em;
+}
+
+:root {
+  --heroui-primary: 217.2 91.2% 59.8%; /* 自然的现代蓝 */
+  --heroui-primary-foreground: 210 40% 98%;
+  --heroui-radius: 0.75rem;
+  --text-primary: 222.2 47.4% 11.2%;
+  --text-secondary: 215.4 16.3% 46.9%;
+}
+
+h1, h2, h3, h4, h5, h6 {
+  color: hsl(var(--text-primary));
+  letter-spacing: -0.02em;
+}
+
+.dark h1, .dark h2, .dark h3, .dark h4, .dark h5, .dark h6 {
+  color: hsl(210 40% 98%);
+}
+
+.dark {
+  --heroui-primary: 217.2 91.2% 59.8%;
+  --heroui-primary-foreground: 210 40% 98%;
 }
 
 @layer components {
@@ -34,23 +64,29 @@ body {
   }
 }
 
+::selection {
+  background-color: #ffcdba;
+  color: #fff;
+}
+
 ::-webkit-scrollbar {
-  width: 8px;
-  height: 8px;
+  width: 6px;
+  height: 6px;
 }
 
 ::-webkit-scrollbar-track {
   background-color: transparent;
-  -webkit-border-radius: 2em;
-  -moz-border-radius: 2em;
-  border-radius: 2em;
+  border-radius: 3px;
 }
 
 ::-webkit-scrollbar-thumb {
-  background-color: rgb(147, 147, 153, 0.5);
-  -webkit-border-radius: 2em;
-  -moz-border-radius: 2em;
-  border-radius: 2em;
+  background-color: rgba(255, 182, 193, 0.4); /* 浅粉色滚动条 */
+  border-radius: 3px;
+  transition: all 0.3s;
+}
+
+::-webkit-scrollbar-thumb:hover {
+  background-color: rgba(255, 127, 172, 0.6);
 }
 
 .monaco-editor {