fix: use StdRng for shuffling indices in fill_block function

k-tv-backend/domain/src/services/schedule/fill.rs

@@ -1,6 +1,8 @@
 use std::collections::HashSet;
 
+use rand::rngs::StdRng;
 use rand::seq::SliceRandom;
+use rand::SeedableRng;
 
 use crate::entities::MediaItem;
 use crate::value_objects::{FillStrategy, MediaItemId};
@@ -20,7 +22,7 @@ pub(super) fn fill_block<'a>(
         }
         FillStrategy::Random => {
             let mut indices: Vec<usize> = (0..pool.len()).collect();
-            indices.shuffle(&mut rand::thread_rng());
+            indices.shuffle(&mut StdRng::from_entropy());
             let mut remaining = target_secs;
             let mut result = Vec::new();
             for i in indices {