Zg/codebase refactor (#20)

Zg/add openai (#18)

more explicit control flow

Add database for persisting votes, and functions to write to db, update submit_voting_results function to write results to DB

Update Hume integration to use OCTAVE TTS endpoint, update Elevenlabs integration to use voice design endpoint, no longer specify voice since voices are now generated

Add formatter (black) and format all code in src directory— using black default formatting configuration

Restore encapsulation for ElevenLabs integration, update TTS functions to return the voice name in addition to the audio

Update UI to compare Hume vs Elevenlabs 50% of the time, and Hume vs Hume 50% of the time

Improve Hume API error handling

Improve ElevenLabs API error handling

Improve Anthropic API error handling

Adds ElevenLabs integration

Add base Hume integration

Organize project structure