fix(phpmyadmin): raise PHP upload limit so SQL imports over 2MB work

Without UPLOAD_LIMIT the phpMyAdmin image keeps PHP's default 2M
post_max_size/upload_max_filesize, so importing any SQL file larger
than 2MB fails with 'POST Content-Length exceeds the limit of
2097152 bytes' followed by a session_start error page.

- Add UPLOAD_LIMIT (512M) and MAX_EXECUTION_TIME (600) env vars,
  configurable from the template env
- Wire the previously unused MYSQL_DATABASE env var into the compose
  file, replacing the hardcoded 'tu_base_de_datos' placeholder, and
  default it to 'phpmyadmin' instead of the system 'mysql' schema

Closes #236

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

blueprints/phpmyadmin/docker-compose.yml

@@ -5,7 +5,7 @@ services:
     image: mysql:5.7
     environment:
       MYSQL_ROOT_PASSWORD: ${MYSQL_ROOT_PASSWORD}
-      MYSQL_DATABASE: tu_base_de_datos
+      MYSQL_DATABASE: ${MYSQL_DATABASE}
       MYSQL_USER: ${MYSQL_USER}
       MYSQL_PASSWORD: ${MYSQL_PASSWORD}
     volumes:
@@ -19,6 +19,8 @@ services:
       PMA_USER: ${MYSQL_USER}
       PMA_PASSWORD: ${MYSQL_PASSWORD}
       PMA_ARBITRARY: 1
+      UPLOAD_LIMIT: ${UPLOAD_LIMIT}
+      MAX_EXECUTION_TIME: ${MAX_EXECUTION_TIME}
     depends_on:
       - db
 

blueprints/phpmyadmin/template.toml

@@ -13,6 +13,8 @@ host = "${main_domain}"
 
 [config.env]
 MYSQL_ROOT_PASSWORD = "${root_password}"
-MYSQL_DATABASE = "mysql"
+MYSQL_DATABASE = "phpmyadmin"
 MYSQL_USER = "phpmyadmin"
 MYSQL_PASSWORD = "${user_password}"
+UPLOAD_LIMIT = "512M"
+MAX_EXECUTION_TIME = "600"