Six modules take their secrets from files; the rest say precisely why not

From the survey of every env-file secret (ADR 0086, issue 041): amqp-ping,
minio, mongodb and grafana use the _FILE twin their software honours;
mesh-catalog and model-usage read DATABASE_URL_FILE (a file the mesh
templates, mounted where only the runtime reads it); grafana's secret files
belong to its own account. Two dead deliveries removed: a line nothing read
in amqp-email-forwarder, and mailu's secret.env on four containers that
never read it. The 25 exceptions that remain carry the surveyed reason —
convertible and awaiting a bed, convertible through a generated config file,
the application's own code, or not convertible.

modules/minio/module.json

@@ -63,7 +63,7 @@
       "type": "file",
       "path": "/var/lib/minio/root.env",
       "mode": "0600",
-      "content": "MINIO_ROOT_USER=meshroot\nMINIO_ROOT_PASSWORD=${secret:root}\n"
+      "content": "MINIO_ROOT_USER=meshroot\n"
     },
     {
       "id": "data",
@@ -95,9 +95,12 @@
         "9000"
       ],
       "volumes": [
-        "/services/minio/data/data1-1:/data"
+        "/services/minio/data/data1-1:/data",
+        "/var/lib/minio/root.secret:/run/secrets/root:ro"
       ],
-      "secrets-in-environment": "the image reads its configuration from the environment only; converting to a file is the per-module work of issue 041"
+      "env": {
+        "MINIO_ROOT_PASSWORD_FILE": "/run/secrets/root"
+      }
     },
     {
       "id": "runtime",