Rewrote app to enable saving, browsing & searching transcriptions.

[hayabhay]

Since there was some apetite for this, I've rewritten this to make it a tad cleaner with a few additional features based on issues raised and personal preferences.

1. Ability to download entire YouTube playlists and upload multiple files at once
2. Ability browse, filter, and search through saved audio files (For now, this is done with a simple SQLite database & SQLAlchemy ORM)
3. Auto-export of transcriptions in multiple formats (was a feature request)
4. Simple substring based search for transcript segments. This is done with a simple LIKE query on the SQLite database.
5. Fully reworked UI with a cleaner layout and more intuitive navigation.
6. Ability to save whisper configurations and reuse to prevent having to re-enter the same parameters every time.
7. Removed the ability to crop audio after download to simplify the codebase. Also, temporarily removed summarization until GPT-3 integration is complete.