feat(deezer): add Flow, Radios and Top Charts as recommendations (#3077)

* feat(deezer): add Flow, Radios and Top Charts as dynamic playlists

Implements recommendations for Deezer provider:
- User's personalized Flow as a virtual playlist
- All available Deezer Radios (genres, moods, etc.)
- Top Charts by country

These appear under the Recommendations panel and use virtual
playlist objects (in_library=false) for dynamic content.

Tested on dev environment and working as expected.

* fix: add missing type annotations for mypy

* Extract virtual playlist IDs and radio IDs into module-level constants