chore: update default account and add example data

- Update default login email to xinmi@local.com
- Update default password to 12345678 (and bcrypt hash in crm.sql)
- Add example customers, products, and contracts to init SQL
- Fix Docker env interpolation for VITE_API_BASE_URL
- Hardcode local backend API URL in frontend .env files
- Update README and docs to reflect new default credentials

server/config.docker.yaml

@@ -35,7 +35,7 @@ file:
 mail:
   smtp: smtp.qq.com
   secret: dhsepilzlvoaceij
-  sender: 1655064994@qq.com
+  sender: xinmi@local.com
 
 # 支付宝支付服务配置
 alipay: