implement native Deezer download/decrypt pipeline

Replace Deezer yt-dlp usage with native ARL session + media.get_url resolution, add BF_CBC_STRIPE decryption in downloader, and wire cipher-aware Deezer downloads through the main rip pipeline. Includes validation hardening and metadata/source-id improvements used by tagging flows.

internal/provider/provider.go

@@ -6,6 +6,8 @@ type Downloadable struct {
 	URL       string
 	Extension string
 	Source    string
+	Cipher    string
+	TrackID   string
 }
 
 type Client interface {