Add support for reference highlighting

[dilithjay]

This PR adds support for reference highlighting when using STATIC_PARSE with pdfplumber. A function (find_bboxes_for_substring) is also provided to find the correct bounding boxes corresponding to a given substring.

A new example notebook (example_notebook_reference_highlight.ipynb) has been added to demonstrate how it can be used.

There are 2 optional params for find_bboxes_for_substring:

• fuzzy (default: False): If True, finds the best approximate match (min word-level edit distance)
• all_matches (default: False): If True, return bounding boxes for all occurrences of the substring

[Copilot]

Pull Request Overview

This PR adds support for reference highlighting when using STATIC_PARSE with pdfplumber. The implementation enables locating bounding boxes for text substrings within PDF documents, supporting both exact and fuzzy matching.

• Adds a new utility function find_bboxes_for_substring with fuzzy matching capabilities
• Modifies PDF parsing to track word-level bounding boxes alongside content extraction
• Updates return types to include bounding box metadata for downstream highlighting

Reviewed Changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 3 comments.

File	Description
lexoid/core/utils.py	Adds text processing utilities and the main find_bboxes_for_substring function with fuzzy matching support
lexoid/core/parse_type/static_parser.py	Updates PDF parsing to collect and return word bounding boxes alongside extracted content

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[pramitchoudhary]

Minor suggestions otherwise LGTM