feat: 集成 DeepSeek AI 服务

- 新增 backend 服务 (Express + TypeScript)
- 前端表单提交改为调用后端 API
- DeepSeek 增强分析结果，本地规则作为 fallback
- Docker 双容器部署：web (Nginx) + backend
- Nginx 反向代理 /api 到后端服务
- 本地开发支持 Vite 代理 + backend:dev 脚本

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

shared/types.ts

@@ -0,0 +1,59 @@
+export interface UserInput {
+  birthDate: string;
+  birthTime: string;
+  gender: 'male' | 'female';
+  birthPlace: string;
+}
+
+export interface FortuneProfile {
+  wuxing: 'wood' | 'fire' | 'earth' | 'metal' | 'water';
+  wuxingLabel: string;
+  personality: string[];
+  strengths: string[];
+  weaknesses: string[];
+  developmentRhythm: 'stable' | 'growth' | 'breakthrough' | 'accumulation';
+}
+
+export interface CompanyRecommendation {
+  type: string;
+  matchScore: number;
+  reasons: string[];
+  suitableFor: string[];
+  notSuitableFor: string[];
+  stageAdvice: string;
+}
+
+export interface JobRecommendation {
+  category: string;
+  matchScore: number;
+  reasons: string[];
+  suitableWorkStyle: string[];
+  notSuitableFor: string[];
+}
+
+export interface StageAdvice {
+  overall: string;
+  careerDirection: string;
+  jobChangeTiming: string;
+  platformPreference: string;
+  keyObservations: string[];
+}
+
+export interface FortuneResult {
+  profile: FortuneProfile;
+  companyRecommendations: CompanyRecommendation[];
+  jobRecommendations: JobRecommendation[];
+  stageAdvice: StageAdvice;
+}
+
+export interface FortuneAnalyzeMeta {
+  provider: 'deepseek';
+  model: string;
+  fallbackUsed: boolean;
+}
+
+export interface FortuneAnalyzeResponse {
+  success: boolean;
+  data: FortuneResult;
+  meta: FortuneAnalyzeMeta;
+}