refactor(styles): migrate from CSS variables to Tailwind classes

- Replace all CSS custom properties with Tailwind utility classes
- Add tailwind.config.js with custom color palette matching Linear design
- Reduce index.css from 89 to 37 lines (58% reduction)
- Maintain consistent visual appearance with semantic color usage
- Update all components to use Tailwind classes instead of CSS variables

src/index.css

@@ -1,89 +1,37 @@
 @import "tailwindcss";
 
-/* Linear 风格的全局配色和基础样式 */
-:root {
-  /* Linear 配色方案 */
-  --color-bg-primary: #fafafa;
-  --color-bg-secondary: #ffffff;
-  --color-bg-tertiary: #f4f4f5;
-  --color-border: #e4e4e7;
-  --color-border-hover: #d4d4d8;
-
-  /* 蓝色主色调 */
-  --color-primary: #3498db;
-  --color-primary-hover: #2980b9;
-  --color-primary-light: #5dade2;
-
-  /* 文本颜色 */
-  --color-text-primary: #18181b;
-  --color-text-secondary: #71717a;
-  --color-text-tertiary: #a1a1aa;
-
-  /* 状态颜色 */
-  --color-success: #10b981;
-  --color-success-light: #d1fae5;
-  --color-error: #ef4444;
-  --color-error-light: #fee2e2;
-  --color-warning: #f59e0b;
-  --color-warning-light: #fef3c7;
-
-  /* 阴影 */
-  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
-  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
-  --shadow-lg:
-    0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
-
-  /* 圆角 */
-  --radius-sm: 0.375rem;
-  --radius-md: 0.5rem;
-  --radius-lg: 0.75rem;
-
-  /* 字体 */
-  --font-family:
-    -apple-system, BlinkMacSystemFont, "Segoe UI", "Roboto", "Helvetica Neue",
-    Arial, sans-serif;
-}
-
+/* 全局基础样式 */
 * {
   box-sizing: border-box;
 }
 
 html {
-  font-family: var(--font-family);
+  @apply font-sans antialiased;
   line-height: 1.5;
-  -webkit-font-smoothing: antialiased;
-  -moz-osx-font-smoothing: grayscale;
 }
 
 body {
-  margin: 0;
-  padding: 0;
-  background-color: var(--color-bg-primary);
-  color: var(--color-text-primary);
-  font-size: 14px;
+  @apply m-0 p-0 bg-gray-50 text-gray-900 text-sm;
 }
 
 /* 滚动条样式 */
 ::-webkit-scrollbar {
-  width: 6px;
-  height: 6px;
+  @apply w-1.5 h-1.5;
 }
 
 ::-webkit-scrollbar-track {
-  background: var(--color-bg-tertiary);
+  @apply bg-gray-100;
 }
 
 ::-webkit-scrollbar-thumb {
-  background: var(--color-border-hover);
-  border-radius: 3px;
+  @apply bg-gray-300 rounded;
 }
 
 ::-webkit-scrollbar-thumb:hover {
-  background: var(--color-text-tertiary);
+  @apply bg-gray-400;
 }
 
 /* 焦点样式 */
 *:focus-visible {
-  outline: 2px solid var(--color-primary);
-  outline-offset: 2px;
+  @apply outline-2 outline-blue-500 outline-offset-2;
 }