fix: an application a device does not offer does not start either

Taking the launcher off the bar is half of a feature switch. The command
has to refuse as well, or a device that does not offer an application can
still be talked into running it by a stale desktop entry, a leftover
window rule or a technician's muscle memory.

Wonder Ink already did this. Parent Call now does the same, through the
same helper and with the same default: absent means yes, so every
existing room is unaffected.

Co-Authored-By: Claude Opus 5 <[email protected]>

tests/test-classroom-desktop-layout.sh

@@ -211,6 +211,19 @@ else:
           every and every["config"].get(
               "org.kde.plasma.icontasks.separateLaunchers") == "true")
 
+print("7. a disabled application does not start either")
+# Taking the launcher off the bar is half of it. The command itself has
+# to refuse, so a device that does not offer an application cannot be
+# talked into running it by a stale desktop entry or a technician's
+# muscle memory.
+for script, setting in (("classroom-wonderink", "WONDERINK_ENABLED"),
+                        ("classroom-parent-call", "PARENT_CALL_ENABLED")):
+    text = (root / "scripts" / script).read_text()
+    check(f"{script} refuses when {setting} is false",
+          setting in text and "not starting" in text)
+    check(f"{script} defaults to starting, so existing rooms are unaffected",
+          'default=True' in text or 'feature(' in text)
+
 print()
 print(f"{passed} passed, {failed} failed")
 raise SystemExit(1 if failed else 0)