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/README.md

@@ -45,3 +45,10 @@ setting once issue 168 closes, not a file the next push would overwrite.
 
 - `x11-display` and the `xinitrc` slot are ADR 0208's. Until the controller knows them, `mctl` reads
   them as unknown.
+
+## Its i3 lines are a contribution (changed 2026-10-05, novox/hq ADR 0212)
+
+The module no longer writes a file into i3's `config.d`. Its window-manager lines (the source is still
+under `files/i3/` where it had one) are a contribution to `node-display-session`. The i3 module places
+them in its own configuration under a `# <module>` line, so this module depends on a window manager
+being assigned beside it.