Take the catalogue's composition rules into the node-engine

ADR 0593 §7: the composer with its refusals leaves mesh-sdk, so mesh-sdk
carries no composition rule. The catalogue functions only the
node-engine's composition reaches (Resolve, Resolution's Compose,
Declaration, DataItems, LeftOut, Rules and the rest, the settings,
placeholder and template refusals, the rendering helpers) are copied
with their tests into internal/compose/resolution; a method of a
mesh-sdk shape becomes a function taking it first. The composition
calls its own copies, and the captured catalogue its tests read lives
here now, shared by mesh-compose's tests.

Claude-Session: https://claude.ai/code/session_01NcbgfJ9Gum47zkFKWRaovL

testdata/beside/mesh-catalog/modules/slack/files/display-session

@@ -0,0 +1,11 @@
+# Slack (module slack, novox/hq ADR 0208, ADR 0212). Owned by the mesh: replaced at every push.
+# Its one start: at login, to the tray (-s), with the arguments of the package's own desktop entry.
+# No XDG autostart entry starts it as well; slack_check names one if it appears.
+exec --no-startup-id /usr/bin/slack --gtk-version=3 -s
+# The chat window. Slack owns four X windows, and the only one i3 manages has the class "slack" in
+# lower case; the three of class "Slack" (the packaged entry's StartupWMClass) are its unmanaged
+# helpers and its tray icon, so a rule on class="Slack" matches nothing. window_role keeps a call or
+# screen-share window out of the rules. $ws3 is i3's, in scope here.
+for_window [class="(?i)^slack$" window_role="browser-window"] move to workspace $ws3
+for_window [class="(?i)^slack$" window_role="browser-window"] floating disable
+for_window [class="(?i)^slack$" window_role="browser-window"] border pixel 2