cleanup docker image

[AEnterprise]

use alpine minimal base image significantly reduce double data storage in different layers use php-fpm daemon for more efficient and faster php execution

image size 437.4MB => 337.8MB, 23% less

some improvements to consider for the future

• the vendor folder is massive, especially with the aws sdk taking 40MB+. maybe another library can do the same with less bloat? i doubt we really need all that
• probably possible to do some more fine tuning of php-fpm in the future to work more optimized for koel but i stuck to mostly default for now