fix: pin PocketBase version and improve documentation

- Pin PocketBase image to v0.22.4 instead of latest
- Add healthcheck to docker-compose.yml
- Add environment variables documentation to README.md
- Add development and production environment sections

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/README.md

@@ -14,3 +14,22 @@ docker-compose up -d
 
 访问: http://localhost:8090/_/
 管理后台: http://localhost:8090/_/ (admin/admin)
+
+## 环境变量
+
+首次启动前，确保 .env 文件包含以下变量：
+
+```env
+PB_PORT=8090
+PB_DATA=./pb_data
+PB_MIGRATIONS=./pb_migrations
+```
+
+## 开发环境
+
+访问管理后台: http://localhost:8090/_/
+首次访问时需要创建管理员账号。
+
+## 生产环境
+
+建议固定 PocketBase 版本并配置反向代理 (nginx)。

backend/docker-compose.yml

@@ -2,7 +2,7 @@ version: '3.8'
 
 services:
   pocketbase:
-    image: ghcr.io/muchobien/pocketbase:latest
+    image: ghcr.io/muchobien/pocketbase:v0.22.4
     container_name: gamegroup-pb
     ports:
       - "${PB_PORT:-8090}:8090"
@@ -12,3 +12,9 @@ services:
     environment:
       - GO_ENV=production
     restart: unless-stopped
+    healthcheck:
+      test: ["CMD", "wget", "--no-verbose", "--tries=1", "--spider", "http://localhost:8090/api/health"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      start_period: 40s