chore: apply phase 0 review fixes

.env.example

@@ -0,0 +1,42 @@
+# Django
+DJANGO_SECRET_KEY=change-me-generate-a-random-secret
+DJANGO_DEBUG=true
+DJANGO_ALLOWED_HOSTS=127.0.0.1,localhost,testserver
+DJANGO_TIME_ZONE=Asia/Shanghai
+
+# MySQL 8.4
+MYSQL_HOST=127.0.0.1
+MYSQL_PORT=3306
+MYSQL_DATABASE=cmhub
+MYSQL_USER=cmhub
+MYSQL_PASSWORD=change-me
+MYSQL_CHARSET=utf8mb4
+
+# AI key encryption
+AI_KEY_ENCRYPTION_KEY=base64-fernet-key
+AI_DEFAULT_CONNECT_TIMEOUT_SECONDS=10
+AI_DEFAULT_READ_TIMEOUT_SECONDS=300
+
+# WeChat Pay V3 native
+WECHAT_PAY_APPID=wx-your-appid
+WECHAT_PAY_MCHID=your-mchid
+WECHAT_PAY_API_V3_KEY=change-me
+WECHAT_PAY_CERT_SERIAL_NO=your-cert-serial-no
+WECHAT_PAY_PRIVATE_KEY_PATH=/secure/wechat/apiclient_key.pem
+WECHAT_PAY_NOTIFY_URL=https://cmhub.example.com/api/v1/recharge/callback/wechat
+
+# Alipay face-to-face payment
+ALIPAY_APPID=your-alipay-appid
+ALIPAY_APP_PRIVATE_KEY_PATH=/secure/alipay/app_private_key.pem
+ALIPAY_PUBLIC_KEY_PATH=/secure/alipay/alipay_public_key.pem
+ALIPAY_NOTIFY_URL=https://cmhub.example.com/api/v1/recharge/callback/alipay
+ALIPAY_DEBUG=false
+
+# Media storage
+STORAGE_BACKEND=local
+MEDIA_ROOT=D:\chengma\cmhub\media
+MEDIA_URL=/media/
+S3_ENDPOINT_URL=https://s3.example.com
+S3_BUCKET_NAME=cmhub-media
+S3_ACCESS_KEY_ID=change-me
+S3_SECRET_ACCESS_KEY=change-me