fix(workspace): probe the dashboard and matomo under the stack's own domain

default.env now sets INFINITO_DOMAIN to main.infinito.test, and CI
deploys under it, but the workspace suite still asserted
https://dashboard.infinito.test. curl could not resolve that host, so
the debian and fedora compose tracks failed after every deploy had
passed. Both URLs now follow INFINITO_DOMAIN once load_repo_env has
loaded it, and an unset domain aborts instead of probing a guess.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

scripts/tests/workspace/utils/common.sh

@@ -9,10 +9,8 @@ DASHBOARD_APP="web-app-dashboard"
 MATOMO_APP="web-app-matomo"
 MARIADB_APP="svc-db-mariadb"
 POSTGRES_APP="svc-db-postgres"
-DASHBOARD_URL="https://dashboard.infinito.test"
-MATOMO_URL="https://matomo.infinito.test"
 
-: "${DASHBOARD_APP}" "${MATOMO_APP}" "${MARIADB_APP}" "${POSTGRES_APP}" "${DASHBOARD_URL}" "${MATOMO_URL}"
+: "${DASHBOARD_APP}" "${MATOMO_APP}" "${MARIADB_APP}" "${POSTGRES_APP}"
 
 UTILS_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 REPO_ROOT="$(cd "${UTILS_DIR}/../../../.." && pwd)"
@@ -57,6 +55,11 @@ load_repo_env() {
 load_repo_env
 ensure_git_safe_directory
 
+DASHBOARD_URL="https://dashboard.${INFINITO_DOMAIN:?load_repo_env did not provide INFINITO_DOMAIN}"
+MATOMO_URL="https://matomo.${INFINITO_DOMAIN:?load_repo_env did not provide INFINITO_DOMAIN}"
+
+: "${DASHBOARD_URL}" "${MATOMO_URL}"
+
 # Print the generated inventory and host_vars for debugging and verification.
 #
 # Matrix-variant deploys write `${INFINITO_INVENTORY_DIR}-0/devices.yml`,