Add headless UI-layout robustness test

Asserts computed Control geometry instead of pixels: HUD/menu stay on-screen,
text fits its box, tap targets >=44px, and the options scroll can reach its
overflow -- across five resolutions plus a +40% pseudo-locale pass. Wired into
run_tests.sh and the CLAUDE.md test list. 16/16 pass headless.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CmG3mQGVXZUPDVapmdbWZ1

run_tests.sh

@@ -26,6 +26,10 @@ echo ""
 echo "=== Touch control tests (joystick self-heals, never strands) ==="
 "$GODOT" --headless --script tests/touch_controls_test.gd
 
+echo ""
+echo "=== UI layout tests (HUD stays on-screen, text fits, tap targets, scroll — across resolutions) ==="
+"$GODOT" --headless --script tests/ui_layout_test.gd
+
 echo ""
 echo "=== Rigid-skin tests (web mesh conversion keeps all materials) ==="
 "$GODOT" --headless --script tests/rigid_skin_test.gd