feat: 初始化 PicAnalysis 项目

完整的前后端图片分析应用，包含：
- 后端：Express + Prisma + SQLite，101个单元测试全部通过
- 前端：React + TypeScript + Vite，47个单元测试，89.73%覆盖率
- E2E测试：Playwright 测试套件
- MCP集成：Playwright MCP配置完成并测试通过

功能模块：
- 用户认证（JWT）
- 文档管理（CRUD）
- 待办管理（三态工作流）
- 图片管理（上传、截图、OCR）

测试覆盖：
- 后端单元测试：101/101 ✅
- 前端单元测试：47/47 ✅
- E2E测试：通过 ✅
- MCP Playwright测试：通过 ✅

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

backend/prisma/schema.prisma

@@ -0,0 +1,176 @@
+// Prisma Schema - 图片OCR与智能文档管理系统
+
+generator client {
+  provider = "prisma-client-js"
+}
+
+datasource db {
+  provider = "sqlite"
+  url      = env("DATABASE_URL")
+}
+
+// 用户
+model User {
+  id            String    @id @default(uuid())
+  username      String    @unique
+  email         String?   @unique
+  password_hash String
+  created_at    DateTime  @default(now())
+  updated_at    DateTime  @updatedAt
+
+  documents     Document[]
+  todos         Todo[]
+  categories    Category[]
+  tags          Tag[]
+  images        Image[]
+  configs       Config[]
+
+  @@map("users")
+}
+
+// 文档
+model Document {
+  id          String   @id @default(uuid())
+  user_id     String
+  title       String?
+  content     String
+  category_id String?
+  created_at  DateTime @default(now())
+  updated_at  DateTime @updatedAt
+
+  user        User           @relation(fields: [user_id], references: [id], onDelete: Cascade)
+  category    Category?      @relation(fields: [category_id], references: [id])
+  images      Image[]
+  todos       Todo[]
+  aiAnalysis  AIAnalysis?
+
+  @@index([user_id])
+  @@index([category_id])
+  @@map("documents")
+}
+
+// 图片
+model Image {
+  id                String   @id @default(uuid())
+  user_id           String
+  document_id       String?
+  file_path         String
+  file_size         Int
+  mime_type         String
+  ocr_result        String?
+  ocr_confidence    Float?
+  processing_status String   @default("pending")
+  quality_score     Float?
+  error_message     String?
+  created_at        DateTime @default(now())
+  updated_at        DateTime @updatedAt
+
+  user              User      @relation(fields: [user_id], references: [id], onDelete: Cascade)
+  document          Document? @relation(fields: [document_id], references: [id], onDelete: SetNull)
+
+  @@index([user_id])
+  @@index([processing_status])
+  @@index([document_id])
+  @@map("images")
+}
+
+// 待办事项
+model Todo {
+  id           String    @id @default(uuid())
+  user_id      String
+  document_id  String?
+  title        String
+  description  String?
+  priority     String    @default("medium")
+  status       String    @default("pending")
+  due_date     DateTime?
+  category_id  String?
+  completed_at DateTime?
+  confirmed_at DateTime?
+  created_at   DateTime  @default(now())
+  updated_at   DateTime  @updatedAt
+
+  user         User      @relation(fields: [user_id], references: [id], onDelete: Cascade)
+  document     Document? @relation(fields: [document_id], references: [id], onDelete: SetNull)
+  category     Category? @relation(fields: [category_id], references: [id])
+
+  @@index([user_id])
+  @@index([status])
+  @@index([category_id])
+  @@map("todos")
+}
+
+// 分类
+model Category {
+  id            String   @id @default(uuid())
+  user_id       String
+  name          String
+  type          String
+  color         String?
+  icon          String?
+  parent_id     String?
+  sort_order    Int      @default(0)
+  usage_count   Int      @default(0)
+  is_ai_created Boolean  @default(false)
+  created_at    DateTime @default(now())
+
+  user          User       @relation(fields: [user_id], references: [id], onDelete: Cascade)
+  parent        Category?  @relation("CategoryToCategory", fields: [parent_id], references: [id])
+  children      Category[] @relation("CategoryToCategory")
+  documents     Document[]
+  todos         Todo[]
+
+  @@index([user_id])
+  @@index([type])
+  @@map("categories")
+}
+
+// 标签
+model Tag {
+  id            String   @id @default(uuid())
+  user_id       String
+  name          String
+  color         String?
+  usage_count   Int      @default(0)
+  is_ai_created Boolean  @default(false)
+  created_at    DateTime @default(now())
+
+  user User @relation(fields: [user_id], references: [id], onDelete: Cascade)
+
+  @@unique([user_id, name])
+  @@index([user_id])
+  @@map("tags")
+}
+
+// AI分析结果
+model AIAnalysis {
+  id                String   @id @default(uuid())
+  document_id       String   @unique
+  provider          String
+  model             String
+  suggested_tags    String
+  suggested_category String?
+  summary           String?
+  raw_response      String
+  created_at        DateTime @default(now())
+
+  document Document @relation(fields: [document_id], references: [id], onDelete: Cascade)
+
+  @@map("ai_analyses")
+}
+
+// 配置
+model Config {
+  id        String   @id @default(uuid())
+  user_id   String
+  key       String
+  value     String
+  created_at DateTime @default(now())
+  updated_at DateTime @updatedAt
+
+  user User @relation(fields: [user_id], references: [id], onDelete: Cascade)
+
+  @@unique([user_id, key])
+  @@index([user_id])
+  @@map("configs")
+}