feat: 新增大量社区功能与基础组件，优化站点整体体验

- 新增事件总线式toast通知系统
- 新增头像、阅读进度、404/500错误页等基础组件
- 重构页脚、布局、分页、点赞按钮等现有组件
- 新增用户个人页、通知中心、帖子编辑/发布/置顶/推荐管理功能
- 优化登录注册页面样式与交互
- 修复路径类型文件引用，更新站点元信息与字体配置

frontend/components/Icons.tsx

@@ -0,0 +1,84 @@
+// 统一的细线统计图标（避免 emoji 渲染不一致）
+interface IconProps {
+  size?: number;
+  filled?: boolean;
+  className?: string;
+}
+
+export function IconComment({ size = 14, className }: IconProps) {
+  return (
+    <svg
+      width={size}
+      height={size}
+      viewBox="0 0 24 24"
+      fill="none"
+      stroke="currentColor"
+      strokeWidth={2}
+      strokeLinecap="round"
+      strokeLinejoin="round"
+      className={className}
+      aria-hidden
+    >
+      <path d="M21 11.5a8.38 8.38 0 0 1-.9 3.8 8.5 8.5 0 0 1-7.6 4.7 8.38 8.38 0 0 1-3.8-.9L3 21l1.9-5.7a8.38 8.38 0 0 1-.9-3.8 8.5 8.5 0 0 1 4.7-7.6 8.38 8.38 0 0 1 3.8-.9h.5a8.48 8.48 0 0 1 8 8v.5z" />
+    </svg>
+  );
+}
+
+export function IconEye({ size = 14, className }: IconProps) {
+  return (
+    <svg
+      width={size}
+      height={size}
+      viewBox="0 0 24 24"
+      fill="none"
+      stroke="currentColor"
+      strokeWidth={2}
+      strokeLinecap="round"
+      strokeLinejoin="round"
+      className={className}
+      aria-hidden
+    >
+      <path d="M1 12s4-8 11-8 11 8 11 8-4 8-11 8-11-8-11-8z" />
+      <circle cx="12" cy="12" r="3" />
+    </svg>
+  );
+}
+
+export function IconHeart({ size = 14, filled, className }: IconProps) {
+  return (
+    <svg
+      width={size}
+      height={size}
+      viewBox="0 0 24 24"
+      fill={filled ? "currentColor" : "none"}
+      stroke="currentColor"
+      strokeWidth={2}
+      strokeLinecap="round"
+      strokeLinejoin="round"
+      className={className}
+      aria-hidden
+    >
+      <path d="M20.84 4.61a5.5 5.5 0 0 0-7.78 0L12 5.67l-1.06-1.06a5.5 5.5 0 0 0-7.78 7.78l1.06 1.06L12 21.23l7.78-7.78 1.06-1.06a5.5 5.5 0 0 0 0-7.78z" />
+    </svg>
+  );
+}
+
+export function StatItem({
+  icon,
+  value,
+  accent,
+}: {
+  icon: React.ReactNode;
+  value: number | string;
+  accent?: boolean;
+}) {
+  return (
+    <span
+      className="inline-flex items-center gap-1.5 meta"
+      style={accent ? { color: "var(--accent)" } : undefined}
+    >
+      {icon}
+      {value}
+    </span>
+  );
+}