feat(chat): enhance chat functionality with song integration and UI improvements

- Updated ChatHeader and ChatMessage components to support song selection and display.
- Enhanced useContentPanel to handle both film and song content, allowing for richer interactions.
- Improved FilmCard and added SongCard components for better media representation.
- Refactored environment variables for better configuration management.
- Updated .gitignore to include development chat history.

Made-with: Cursor

packages/app/public/images/loading-poster.svg

@@ -0,0 +1,24 @@
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