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/amqp-ping/module.json

@@ -36,7 +36,7 @@
       "type": "file",
       "path": "/var/lib/amqp-ping/amqp.env",
       "mode": "0600",
-      "content": "MESH_AMQP_HOST=${bound:amqp:at}\nMESH_AMQP_PORT=${bound:amqp:port}\nMESH_AMQP_USER=${bound:amqp:as}\nMESH_AMQP_VHOST=${bound:amqp:as}\nMESH_AMQP_PASSWORD=${secret:amqp}\n"
+      "content": "MESH_AMQP_HOST=${bound:amqp:at}\nMESH_AMQP_PORT=${bound:amqp:port}\nMESH_AMQP_USER=${bound:amqp:as}\nMESH_AMQP_VHOST=${bound:amqp:as}\n"
     },
     {
       "id": "net",
@@ -49,10 +49,12 @@
       "name": "amqp-ping",
       "network": "amqp-ping",
       "volumes": [
-        "/var/lib/mesh/amqp-ping/broker:/run/secrets/broker:ro"
+        "/var/lib/mesh/amqp-ping/broker:/run/secrets/broker:ro",
+        "/var/lib/amqp-ping/amqp.secret:/run/secrets/amqp:ro"
       ],
       "env": {
-        "MESH_BROKER_FILE": "/run/secrets/broker"
+        "MESH_BROKER_FILE": "/run/secrets/broker",
+        "MESH_AMQP_PASSWORD_FILE": "/run/secrets/amqp"
       },
       "env-file": [
         "/var/lib/amqp-ping/amqp.env"
@@ -60,8 +62,7 @@
       "restart-on": [
         "amqp-env"
       ],
-      "artifact": "runtime",
-      "secrets-in-environment": "the runtime reads MESH_AMQP_* from the environment; a file twin in the SDK is the per-module work of issue 041"
+      "artifact": "runtime"
     }
   ],
   "build": {