i3: other modules' lines are contributions to node-display-session (hq ADR 0212)

rofi, clipmenu, feh, i3status-rust and the laptop's model module wrote files into i3's config.d,
naming no dependency on the window manager. They now contribute their lines; i3 places them under a
line naming each module, and config.d is the operator's alone. The catalogue-wide test composes the
contributions as the controller does and checks the whole with i3 -C.

modules/feh/module.json

@@ -38,14 +38,6 @@
       "owner": "${machine:account}",
       "mode": "0755",
       "content": "#!/bin/sh\n# The wallpaper (module feh, novox/hq ADR 0208). Owned by the mesh: replaced at every push. The\n# session's start runs it, and so may anything that wants the declared wallpaper back. The image is\n# the module's own, in ~/.local/share/feh/wallpapers. feh_set changes the wallpaper for a session\n# without touching this file.\nfeh --no-fehbg --bg-fill \"$HOME/.local/share/feh/wallpapers/default.jpg\"\n"
-    },
-    {
-      "id": "i3-bindings",
-      "type": "file",
-      "path": "${machine:account-home}/.config/i3/config.d/50-feh.conf",
-      "owner": "${machine:account}",
-      "mode": "0644",
-      "content": "# The wallpaper's key (module feh, novox/hq ADR 0208). Owned by the mesh: replaced at every push.\n# It puts the declared wallpaper back, after a monitor change or a wallpaper set for the session.\nbindsym $mod+Shift+b exec --no-startup-id ~/.fehbg\n"
     }
   ],
   "build": {
@@ -67,5 +59,12 @@
         ]
       }
     ]
-  }
+  },
+  "contributions": [
+    {
+      "seat": "node-display-session",
+      "kind": "config",
+      "content": "# The wallpaper's key (module feh, novox/hq ADR 0208). Owned by the mesh: replaced at every push.\n# It puts the declared wallpaper back, after a monitor change or a wallpaper set for the session.\nbindsym $mod+Shift+b exec --no-startup-id ~/.fehbg\n"
+    }
+  ]
 }