fix: 修复 Vercel 部署配置并添加 Neon 数据库文档

- 移除 vercel.json 中不存在的 Secret 引用 (@database_url)
- 在 CLAUDE.md 中添加 Neon 数据库配置说明
- 环境变量应直接在 Vercel Dashboard 中设置

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

CLAUDE.md

@@ -52,6 +52,7 @@ src/app/
 ```
 
 ### Database (Prisma + PostgreSQL)
+- **Provider**: Neon (serverless PostgreSQL)
 - **Schema**: `prisma/schema.prisma` defines models: `Project`, `Tag`, `ExternalLink`, `ProjectTag`
 - **Enums**: `ProjectStatus` (ACTIVE/ARCHIVED), `LinkType` (WEBSITE/GITHUB/HUGGINGFACE/PAPER)
 - **Client singleton**: `src/lib/prisma.ts` exports Prisma client instance
@@ -64,6 +65,13 @@ src/app/
   - `ExternalLink`: `@@unique([projectId, url])` (each project can't have duplicate URLs)
 - **Indexes**: `idx_project_status_createdAt`, `idx_project_slug`, `idx_tag_slug`, `idx_link_projectId`, `idx_link_type`, `idx_link_type_url` (composite for efficient URL-based deduplication)
 
+#### Neon Database Setup
+- **Dashboard**: https://console.neon.tech
+- **Connection String Format**: `postgres://[user]:[password]@[host]/[database]?sslmode=require`
+- **Vercel Integration**: Set `DATABASE_URL` environment variable in Vercel Dashboard (do NOT use `vercel.json` env references)
+- **Free Tier**: 0.5GB storage, 300 hours compute/month
+- **Run Migrations**: After deployment, run `pnpm prisma db push` or use Neon's SQL Editor to create tables
+
 ### Webhook Deduplication Strategy
 The webhook at `src/app/api/webhook/projects/route.ts` implements a **multi-level deduplication** strategy to prevent duplicate projects:
 1. **GitHub URL exact match** (highest priority) - via `ExternalLink` table using `idx_link_type_url` index

vercel.json

@@ -2,8 +2,5 @@
   "buildCommand": "pnpm prisma generate && pnpm build",
   "installCommand": "pnpm install",
   "framework": "nextjs",
-  "regions": ["sin1"],
-  "env": {
-    "DATABASE_URL": "@database_url"
-  }
+  "regions": ["sin1"]
 }