feat: 完善前后端核心功能模块

后端:
- 新增认证(auth)、任务(tasks)、映射(mappings)、对账(reconciliation)、异常(exceptions)、导出(exports) API
- 新增核心模块: database, security, permissions, tenant, exceptions, error_handlers
- 新增数据模型: user, company, reconciliation_task, field_mapping, uploaded_file 等
- 新增服务层: ai_recognizer, file_parser, file_storage, mapping, reconciliation 等
- 添加数据库迁移脚本

前端:
- 新增登录页面和仪表盘页面
- 新增任务列表、任务详情、字段映射页面
- 新增异常处理页面和规则设置页面
- 新增 API 代理路由 /api/[...path]
- 新增 UI 组件库 (button, card, dialog, input, table 等)
- 新增 auth 组件 (ProtectedRoute, PermissionGate)
- 新增 layout 组件 (Header, Sidebar)
- 新增 mapping 组件 (FieldMappingTable, AISuggestionPanel)
- 新增 API 客户端和 hooks (useAsync, useToast, usePermission 等)
- 新增状态管理 (auth-store, company-store, ui-store)
- 集成 Tailwind CSS 和 shadcn/ui 组件库

其他:
- 添加 Alembic 数据库迁移配置
- 添加初始化示例数据脚本
- 更新项目文档

frontend/components/mapping/ConfidenceBadge.tsx

@@ -0,0 +1,46 @@
+"use client";
+
+import { cn } from "@/lib/utils";
+
+interface ConfidenceBadgeProps {
+  confidence: number;
+  showLabel?: boolean;
+  className?: string;
+}
+
+export function ConfidenceBadge({
+  confidence,
+  showLabel = true,
+  className,
+}: ConfidenceBadgeProps) {
+  const getLevel = (value: number) => {
+    if (value > 0.9) return "high";
+    if (value >= 0.7) return "medium";
+    return "low";
+  };
+
+  const getLabel = (value: number) => {
+    if (value > 0.9) return "高";
+    if (value >= 0.7) return "中";
+    return "低";
+  };
+
+  const level = getLevel(confidence);
+  const label = getLabel(confidence);
+
+  return (
+    <span
+      className={cn(
+        "inline-flex items-center px-2 py-0.5 rounded text-xs font-medium",
+        level === "high" && "bg-green-100 text-green-800 dark:bg-green-900 dark:text-green-300",
+        level === "medium" && "bg-yellow-100 text-yellow-800 dark:bg-yellow-900 dark:text-yellow-300",
+        level === "low" && "bg-red-100 text-red-800 dark:bg-red-900 dark:text-red-300",
+        className
+      )}
+    >
+      {showLabel ? label : `${(confidence * 100).toFixed(0)}%`}
+    </span>
+  );
+}
+
+export default ConfidenceBadge;