Merge pull request 'fix: 修复 Dockerfile 运行阶段缺少 config.yaml 导致容器启动 panic' (#127) from develop into v2

Reviewed-on: http://8.161.227.145:3000/XEngineers/CamTalk/pulls/127

backend/Dockerfile

@@ -21,8 +21,9 @@ RUN apk add --no-cache ca-certificates tzdata
 
 WORKDIR /app
 
-# 复制二进制（配置通过 docker-compose env_file 注入）
+# 复制二进制和配置文件（敏感配置通过 docker-compose env_file 注入覆盖）
 COPY --from=builder /camtalk .
+COPY config.yaml .
 
 EXPOSE 8080