fix: keep overlap labels aligned with boxes

[uczltw6]

Summary

• keep bounding boxes, element labels, and text content aligned when an element has no coordinates
• preserve original element indexes in overlap reports
• add a regression test covering a coordinate-less element before a nested pair

Problem

catch_overlapping_and_nested_bboxes() already excludes elements without coordinates from its bounding-box collection, but it still appended their labels and text to the parallel collections. A coordinate-less element therefore shifted those collections, causing later overlap and parent-child reports to name the wrong elements and content.

The fix appends all three values only for coordinate-bearing elements, so every index used by the overlap detector refers to the same source element.

Tests

• python3 -m pytest test_unstructured/test_utils.py -q — 38 passed
• python3 -m ruff check unstructured/utils.py test_unstructured/test_utils.py
• python3 -m ruff format --check unstructured/utils.py test_unstructured/test_utils.py
• git diff --check

AI assistance was used to help identify the edge case and prepare the focused patch. The behavior and test results were verified locally.

[cubic-dev-ai]

No issues found across 4 files

<sub>Shadow auto-approve: would auto-approve. Fix catch_overlapping_and_nested_bboxes() so labels/text are only appended for coordinate-bearing elements, preventing index misalignment in overlap reports. Adds a regression test and bumps version/changelog.

Re-trigger cubic</sub>