refactor: 迁移根目录 docker/ 到 source/docker/，更新所有路径引用

- 将 docker/{nginx.conf,run.sh,zz-phprun.ini,zz-phpfpm.conf} 移动到 source/docker/
- 更新所有 Dockerfile 中 /var/www/html/docker/ -> /var/www/html/source/docker/
- 更新 stack.json managed_files 路径前缀
- 重组 stack 模式目录结构 docker/ -> source/docker/
- 更新 source/README.md 目录描述
- 更新 AdminUpdateServiceBase.php 可选文件前缀

source/stack/docker-dev/Dockerfile

@@ -63,8 +63,8 @@ RUN composer dump-autoload
 # RUN install-php-extensions @composer
 
 # Dev mode PHP config (overrides zz-phprun.ini)
-COPY docker/zzz-dev.ini /usr/local/etc/php/conf.d/zzz-dev.ini
-COPY docker/zzz-xdebug.ini /usr/local/etc/php/conf.d/zzz-xdebug.ini
+COPY source/docker/zzz-dev.ini /usr/local/etc/php/conf.d/zzz-dev.ini
+COPY source/docker/zzz-xdebug.ini /usr/local/etc/php/conf.d/zzz-xdebug.ini
 
 VOLUME /var/www/html/runtime
 VOLUME /var/www/html/public/storage
@@ -77,9 +77,9 @@ VOLUME /var/www/html/storage
 # Expose Nginx port
 EXPOSE 8000
 
-RUN chmod +x /var/www/html/docker/run.sh
+RUN chmod +x /var/www/html/source/docker/run.sh
 
 # Start Nginx and PHP-FPM
-ENTRYPOINT ["/bin/bash", "/var/www/html/docker/run.sh"]
+ENTRYPOINT ["/bin/bash", "/var/www/html/source/docker/run.sh"]
 
 CMD ["server"]