feat: converter keeps layers of screens and camera, perspective, matrix calls; That New Teacher runs its own text-tag libraries

onlayer on show/hide/call screen and `camera <layer>` reach the player, `perspective`
is an ATL property now, RotateMatrix/OffsetMatrix/ScaleMatrix, Text.set_text and
renpy.fetch are accepted. The text-effect modules of That New Teacher are no longer
skipped (only the shader-based wave tag is).

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

backend/tests/test_screens.py

@@ -259,3 +259,14 @@ def test_input_widget_values_and_focus_actions_are_accepted():
     body = data.screens["s"]["body"]
     assert [n.get("w") for n in body[:3]] == ["input", "input", "textbutton"]
     assert "default" in body[1]["props"] and "value" in body[0]["props"]
+
+
+def test_layers_of_screens_and_camera_are_kept():
+    data = parse('screen s:\n    text "x"\n'
+                 'label start:\n    show screen s onlayer hud\n    call screen s onlayer overlay\n'
+                 '    hide screen s onlayer hud\n    camera hud:\n        perspective True\n        zpos 5\n'
+                 '    camera:\n        zoom 2\n')
+    body = data.modules["script.rpy"][0]["body"]
+    assert [(n["op"], n.get("layer")) for n in body] == [
+        ("show_screen", "hud"), ("call_screen", "overlay"), ("hide_screen", "hud"), ("camera", "hud"), ("camera", None)]
+    assert body[3]["at"][-1]["props"] == {"perspective": True, "zpos": 5}