build(docker): optimize image size and security

- add mysql client binaries for database operations
- reduce php extensions to production essentials
- bind mysql and phpmyadmin to localhost only
- replace php-fpm.conf with php.ini for upload limits

docker/Dockerfile

@@ -6,9 +6,9 @@ COPY --from=mysql /usr/bin/mysql /usr/bin/mysql
 COPY --from=mysql /usr/bin/mysqldump /usr/bin/mysqldump
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
-    libonig-dev \
+    libonig-dev libicu-dev \
     gosu netcat-traditional \
- && docker-php-ext-install pdo_mysql mbstring \
+ && docker-php-ext-install pdo_mysql mbstring intl \
  && apt-get clean && rm -rf /var/lib/apt/lists/*
 
 COPY --from=composer:latest /usr/bin/composer /usr/bin/composer