Semantic openai native (de-faiss) / Model-based citation footnote

[michaelthwan]

• Native call openai, no need faiss (and support similarity value)
• de semantic_search_provider config
• de FootnoteService. Now it is FrontendService
• Using prompt_v3

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[michaelthwan]

@panglydia The update is big. Seek your testing/review as well thanks. requirement.txt updated. Suggest to reinstall env.

[panglydia]

@michaelthwan Did below changes & fixes:

• Cleaned up original references in source to prevent confusion in prompt
• Fixed to include only in-scope source in prompt
• Reordered source url_id in prompt & response
• Code clean up

Plz see if u hv further comment on the changes.