feat(llm_aided): add title optimization feature

[myhloli]

• Implement llm_aided_title function to optimize document titles using LLM
• Update pdf_parse_union_core_v2.py to include title optimization
• Modify ocr_mkcontent.py to use optimized title levels
• Add openai SDK dependency in setup.py

Motivation

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Modification

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BC-breaking (Optional)

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Use cases (Optional)

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Checklist

Before PR:

• Pre-commit or other linting tools are used to fix the potential lint issues.
• Bug fixes are fully covered by unit tests, the case that causes the bug should be added in the unit tests.
• The modification is covered by complete unit tests. If not, please add more unit test to ensure the correctness.
• The documentation has been modified accordingly, like docstring or example tutorials.

After PR:

• If the modification has potential influence on downstream or other related projects, this PR should be tested with those projects.
• CLA has been signed and all committers have signed the CLA in this PR.