feat: glpi-test compose — loopback GLPI 11.0.8 + MariaDB 12.3.3 [#769]

Workstation test lane (Charles: GLPI/vault/cloudron-app tests run as
docker on the workstation). Auto-install verified; loopback :8090.

https://projects.knownelement.com/issues/769#note-4152

docker/glpi-test/compose.yaml

@@ -0,0 +1,38 @@
+# glpi-test — loopback GLPI test instance (preprod stand-in for the live
+# GLPI at cmdb.knownelement.com; #705/#774). NOT for prod data.
+services:
+  db:
+    image: mariadb:12.3.3
+    container_name: ukrrs-pfv-glpi-test-db
+    environment:
+      MARIADB_DATABASE: glpidb
+      MARIADB_USER: glpi
+      MARIADB_ROOT_PASSWORD: ${MARIADB_ROOT_PASSWORD:?set in ~/.creds/glpi-test.env}
+      MARIADB_PASSWORD: ${MARIADB_PASSWORD:?set in ~/.creds/glpi-test.env}
+    volumes:
+      - glpi-test-db:/var/lib/mysql
+    restart: unless-stopped
+
+  glpi:
+    image: glpi/glpi:11.0.8
+    container_name: ukrrs-pfv-glpi-test
+    depends_on:
+      - db
+    ports:
+      - "127.0.0.1:8090:80"
+    environment:
+      TIMEZONE: America/Chicago
+      GLPI_DB_HOST: db
+      GLPI_DB_PORT: "3306"
+      GLPI_DB_NAME: glpidb
+      GLPI_DB_USER: glpi
+      GLPI_DB_PASSWORD: ${MARIADB_PASSWORD}
+    volumes:
+      - glpi-test-var:/var/www/html/glpi/files
+      - glpi-test-etc:/etc/glpi
+    restart: unless-stopped
+
+volumes:
+  glpi-test-db:
+  glpi-test-var:
+  glpi-test-etc: