[UI] Detail Screen "Where to Watch" Integration

[mukesh-5059]

Difficulty: Hard
Location: app/src/main/java/com/example/movies_db/ui/screens/MovieDetailScreen.kt
Description:

• Fetch providers asynchronously when the screen opens.
• Display "Flatrate", "Rent", and "Buy" options separately if possible, or aggregate them.
• Handle attribution requirements (TMDB requires "JustWatch" attribution).