icecast: its passwords are a file the mesh writes, not the image's environment

The image seds ICECAST_*_PASSWORD from the environment into /etc/icecast.xml;
ADR 0086 wants secrets as files. icecast starts as root, reads its config, then
drops to uid 100, so a root-owned 0600 icecast.xml rendered with ${secret:...}
and mounted read-only works and the entrypoint's seds never fire (no env set).
The "secrets-in-environment" exemption and server.env are gone.

Also: directories are placed (state, logs owned 100:101 so the image's VOLUME
/var/log/icecast is not an anonymous volume per container, as HAL learned);
the server and sidecar share a module network, so the sidecar reaches
http://icecast:8000 instead of assuming machine port 8000 on the host; the
stream endpoint is routed (label "icecast"), as HAL served it via traefik.
Secrets remain mesh-vault grants (requires secret), now under ${dir:state}.

Verified: catalogue tests with MESH_CATALOGUE pointed at this tree; a
throwaway container of the pinned digest (the one ace runs) with the rendered
file (dummy secrets, root 0600, :ro): runs as icecast, status-json 200,
admin 401 without / 200 with the admin secret, a source PUT with the source
secret mounts, a listener receives it, a wrong source password gets 401, logs
land in the uid-100 directory.

modules/icecast/module.json

@@ -1,6 +1,26 @@
 {
   "module": "icecast",
   "version": "1",
+  "requires": [
+    "route",
+    "secret"
+  ],
+  "contributes": {
+    "route": {
+      "label": "icecast",
+      "endpoint": "stream"
+    }
+  },
+  "binds": {
+    "route": "${dir:state}/route.json"
+  },
+  "secrets": {
+    "secret": {
+      "source": "${dir:state}/source.secret",
+      "admin": "${dir:state}/admin.secret",
+      "relay": "${dir:state}/relay.secret"
+    }
+  },
   "capabilities": [
     "container-runtime"
   ],
@@ -17,7 +37,7 @@
       "port": 8000,
       "protocol": "tcp",
       "from": "mesh",
-      "why": "streams in from sources and out to listeners"
+      "why": "streams in from sources (HTTP PUT) and out to listeners, plus the status and admin pages; a public name is its route"
     }
   ],
   "resources": [
@@ -30,28 +50,43 @@
     {
       "id": "state",
       "type": "directory",
-      "path": "/var/lib/icecast-module",
-      "mode": "0700"
+      "mode": "0700",
+      "place": "."
     },
     {
-      "id": "server-env",
+      "id": "logs",
+      "type": "directory",
+      "mode": "0700",
+      "owner": "100:101"
+    },
+    {
+      "id": "server-conf",
       "type": "file",
-      "path": "/var/lib/icecast-module/server.env",
+      "path": "${dir:state}/icecast.xml",
       "mode": "0600",
-      "content": "ICECAST_SOURCE_PASSWORD=${secret:source}\nICECAST_ADMIN_PASSWORD=${secret:admin}\nICECAST_RELAY_PASSWORD=${secret:relay}\nICECAST_ADMIN_USERNAME=admin\n"
+      "content": "<icecast>\n    <!-- Written by the mesh (modules/icecast). Passwords arrive as secrets rendered into this file,\n         never as environment: the image's entrypoint seds ICECAST_* variables into the file only\n         when they are set, and none are. -->\n    <location>Earth</location>\n    <admin>icemaster@localhost</admin>\n    <limits>\n        <clients>100</clients>\n        <sources>2</sources>\n        <queue-size>524288</queue-size>\n        <client-timeout>30</client-timeout>\n        <header-timeout>15</header-timeout>\n        <source-timeout>10</source-timeout>\n        <burst-on-connect>1</burst-on-connect>\n        <burst-size>65535</burst-size>\n    </limits>\n    <authentication>\n        <source-password>${secret:source}</source-password>\n        <relay-password>${secret:relay}</relay-password>\n        <admin-user>admin</admin-user>\n        <admin-password>${secret:admin}</admin-password>\n    </authentication>\n    <!-- The name icecast writes into playlists (.m3u/.xspf: http://<hostname>:<port>/<mount>) and\n         would announce to YP (none configured). A machine's own name belongs to its assignment, and\n         an assignment merges only into JSON; this XML cannot take it, so the neutral default stays. -->\n    <hostname>localhost</hostname>\n    <listen-socket>\n        <port>8000</port>\n    </listen-socket>\n    <http-headers>\n        <header name=\"Access-Control-Allow-Origin\" value=\"*\" />\n    </http-headers>\n    <fileserve>1</fileserve>\n    <paths>\n        <basedir>/usr/share/icecast</basedir>\n        <logdir>/var/log/icecast</logdir>\n        <webroot>/usr/share/icecast/web</webroot>\n        <adminroot>/usr/share/icecast/admin</adminroot>\n        <alias source=\"/\" destination=\"/status.xsl\"/>\n    </paths>\n    <logging>\n        <accesslog>access.log</accesslog>\n        <errorlog>error.log</errorlog>\n        <loglevel>3</loglevel>\n        <logsize>10000</logsize>\n    </logging>\n    <security>\n        <chroot>0</chroot>\n        <!-- Starts as root, reads this 0600 root-owned file, then drops to the image's icecast user\n             (uid 100, group icecast 101) before serving. -->\n        <changeowner>\n            <user>icecast</user>\n            <group>icecast</group>\n        </changeowner>\n    </security>\n</icecast>\n"
+    },
+    {
+      "id": "net",
+      "type": "network",
+      "name": "icecast"
     },
     {
       "id": "server",
       "type": "container",
       "name": "icecast",
       "image": "infiniteproject/icecast@sha256:cd506cf3dfe31ce05fd37d7e672dbd1213e7255cc93d28ecf5a3b547af4e162c",
-      "env-file": [
-        "/var/lib/icecast-module/server.env"
-      ],
+      "network": "icecast",
       "ports": [
         "8000"
       ],
-      "secrets-in-environment": "the image seds ICECAST_*_PASSWORD into icecast.xml and has no _FILE; convertible by mounting a generated icecast.xml, not yet done"
+      "volumes": [
+        "${dir:state}/icecast.xml:/etc/icecast.xml:ro",
+        "${dir:logs}:/var/log/icecast"
+      ],
+      "restart-on": [
+        "server-conf"
+      ]
     },
     {
       "id": "runtime-config",
@@ -65,14 +100,14 @@
       "id": "runtime",
       "type": "container",
       "name": "mesh-icecast",
-      "network": "host",
+      "network": "icecast",
       "volumes": [
         "/var/lib/mesh/icecast/broker:/run/secrets/broker:ro",
         "/var/lib/mesh/icecast/config.json:/run/config/config.json:ro"
       ],
       "env": {
         "MESH_BROKER_FILE": "/run/secrets/broker",
-        "MESH_ICECAST_URL": "http://127.0.0.1:8000",
+        "MESH_ICECAST_URL": "http://icecast:8000",
         "MESH_ICECAST_CONFIG_FILE": "/run/config/config.json"
       },
       "restart-on": [
@@ -101,15 +136,5 @@
         "from": "Dockerfile"
       }
     ]
-  },
-  "requires": [
-    "secret"
-  ],
-  "secrets": {
-    "secret": {
-      "source": "/var/lib/icecast-module/source.secret",
-      "admin": "/var/lib/icecast-module/admin.secret",
-      "relay": "/var/lib/icecast-module/relay.secret"
-    }
   }
 }