feat: KPL v1.5.0 功能迭代

1. 奖章条件优化
- 修复统计查询 SQL 语法
- 添加按类别检查奖章方法

2. 移动端适配
- 登录页、课程中心、课程详情
- 考试页面、成长路径、排行榜

3. 证书系统
- 数据库模型和迁移脚本
- 证书颁发/列表/下载/验证 API
- 前端证书列表页面

4. 数据大屏
- 企业级/团队级数据 API
- ECharts 可视化大屏页面

frontend/src/api/certificate.ts

@@ -0,0 +1,149 @@
+/**
+ * 证书系统 API
+ */
+import request from '@/utils/request'
+
+// 证书类型
+export type CertificateType = 'course' | 'exam' | 'achievement'
+
+// 证书模板
+export interface CertificateTemplate {
+  id: number
+  name: string
+  type: CertificateType
+  background_url?: string
+  is_active: boolean
+}
+
+// 证书信息
+export interface Certificate {
+  id: number
+  certificate_no: string
+  title: string
+  description?: string
+  type: CertificateType
+  type_name: string
+  issued_at: string
+  valid_until?: string
+  score?: number
+  completion_rate?: number
+  pdf_url?: string
+  image_url?: string
+  course_id?: number
+  exam_id?: number
+  badge_id?: number
+  meta_data?: Record<string, any>
+  template?: {
+    id: number
+    name: string
+    background_url?: string
+  }
+  user?: {
+    id: number
+    username: string
+    full_name?: string
+  }
+}
+
+// 证书列表响应
+export interface CertificateListResponse {
+  items: Certificate[]
+  total: number
+  offset: number
+  limit: number
+}
+
+// 验证结果
+export interface VerifyResult {
+  valid: boolean
+  certificate_no: string
+  title?: string
+  type_name?: string
+  issued_at?: string
+  user?: {
+    id: number
+    username: string
+    full_name?: string
+  }
+}
+
+/**
+ * 获取证书模板列表
+ */
+export function getCertificateTemplates(type?: CertificateType) {
+  return request.get<CertificateTemplate[]>('/certificates/templates', {
+    params: { cert_type: type }
+  })
+}
+
+/**
+ * 获取我的证书列表
+ */
+export function getMyCertificates(params?: {
+  cert_type?: CertificateType
+  offset?: number
+  limit?: number
+}) {
+  return request.get<CertificateListResponse>('/certificates/me', { params })
+}
+
+/**
+ * 获取指定用户的证书列表
+ */
+export function getUserCertificates(userId: number, params?: {
+  cert_type?: CertificateType
+  offset?: number
+  limit?: number
+}) {
+  return request.get<CertificateListResponse>(`/certificates/user/${userId}`, { params })
+}
+
+/**
+ * 获取证书详情
+ */
+export function getCertificateDetail(certId: number) {
+  return request.get<Certificate>(`/certificates/${certId}`)
+}
+
+/**
+ * 获取证书分享图片URL
+ */
+export function getCertificateImageUrl(certId: number): string {
+  return `/api/v1/certificates/${certId}/image`
+}
+
+/**
+ * 获取证书下载URL
+ */
+export function getCertificateDownloadUrl(certId: number): string {
+  return `/api/v1/certificates/${certId}/download`
+}
+
+/**
+ * 验证证书
+ */
+export function verifyCertificate(certNo: string) {
+  return request.get<VerifyResult>(`/certificates/verify/${certNo}`)
+}
+
+/**
+ * 颁发课程证书
+ */
+export function issueCoursCertificate(data: {
+  course_id: number
+  course_name: string
+  completion_rate?: number
+}) {
+  return request.post<Certificate>('/certificates/issue/course', data)
+}
+
+/**
+ * 颁发考试证书
+ */
+export function issueExamCertificate(data: {
+  exam_id: number
+  exam_name: string
+  score: number
+}) {
+  return request.post<Certificate>('/certificates/issue/exam', data)
+}