Skip compositor tests without recording a failure

Two problems made a missing Wayland compositor look like broken tests.

The cleanup traps ended on a bare conditional, so when a test skipped
before creating its TMPDIR the trap's last command returned 1 and, under
set -e, that overrode the explicit exit 0.

Six tests that launch quickshell had no compositor guard at all, so they
ran anyway and failed on the Qt platform plugin.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

test/shell.d/indicator-contract-test.sh

@@ -12,10 +12,17 @@ cleanup() {
     kill "$QS_PID" 2>/dev/null || true
     wait "$QS_PID" 2>/dev/null || true
   fi
-  [[ -n $TMPDIR && -d $TMPDIR ]] && rm -rf "$TMPDIR"
+  if [[ -n $TMPDIR && -d $TMPDIR ]]; then
+    rm -rf "$TMPDIR"
+  fi
 }
 trap cleanup EXIT
 
+if [[ -z ${WAYLAND_DISPLAY:-} ]]; then
+  pass "no Wayland compositor; skipping QML contract test"
+  exit 0
+fi
+
 if ! command -v quickshell >/dev/null 2>&1; then
   pass "quickshell not installed; skipping QML contract test"
   exit 0