chore: snapshot in-progress question-gen work before preflight fixes

tests/integration/test_tree_build_e2e.py

@@ -7,15 +7,20 @@
 from __future__ import annotations
 
 import numpy as np
-import pytest
 
-from app.tree.index import (
-    IndexMeta, TreeIndex, L1Node, L1Card,
-    L2Node, L2Card, L3Node, L3Card,
-)
-from app.tree.verify import verify_tree
-from app.tree.subtitle import SRTEntry, assign_subtitles_voronoi
 from app.tree.environment import TreeEnvironment
+from app.tree.index import (
+    IndexMeta,
+    L1Card,
+    L1Node,
+    L2Card,
+    L2Node,
+    L3Card,
+    L3Node,
+    TreeIndex,
+)
+from app.tree.subtitle import SRTEntry, assign_subtitles_voronoi
+from app.tree.verify import verify_tree
 
 
 class TestTreeModuleE2E: