fix(infra): 修复 worker healthcheck YAML 语法 & APP_VERSION 添加默认值

- Worker healthcheck: 原 python3 单引号嵌套导致 YAML 解析错误，改用 grep -q celery /proc/1/cmdline
- APP_VERSION: 添加 :-unknown 默认值，防止变量缺失时健康检查端点崩溃

infra/docker/compose.yml

@@ -52,7 +52,7 @@ services:
     
     environment:
       APP_ENV: ${APP_ENV:-staging}
-      APP_VERSION: ${APP_VERSION}
+      APP_VERSION: ${APP_VERSION:-unknown}
       GENERATED_FILES_DIR: /app/generated
       GENERATED_FILES_URL_PREFIX: /generated-files
       PUBLIC_API_BASE_URL: ${PUBLIC_API_BASE_URL:-https://api.xiaoxiajianji.com}
@@ -106,7 +106,7 @@ services:
     
     environment:
       APP_ENV: ${APP_ENV:-staging}
-      APP_VERSION: ${APP_VERSION}
+      APP_VERSION: ${APP_VERSION:-unknown}
       WORKER_CONCURRENCY: ${WORKER_CONCURRENCY:-1}
       WORKER_MAX_TASKS_PER_CHILD: ${WORKER_MAX_TASKS_PER_CHILD:-100}
       GENERATED_FILES_DIR: /app/generated
@@ -122,7 +122,7 @@ services:
     # 健康检查配置
     # 注：celery inspect ping 依赖 broker 连接，在容器内不可靠，改用进程检查
     healthcheck:
-      test: ["CMD-SHELL", "python3 -c "import os,sys;sys.exit(0 if any(b'celery' in open(f'/proc/{p}/cmdline','rb').read() for p in os.listdir('/proc') if p.isdigit()) else 1)""]
+      test: ["CMD-SHELL", "grep -q celery /proc/1/cmdline || exit 1"]
       interval: 30s
       timeout: 10s
       retries: 3