hls: cargo fmt + clippy::cloned_ref_to_slice_refs

Pure mechanical pass on the files this branch added/modified:
rustfmt reflow of a few long lines / chains, and the one
non-pre-existing clippy warning — replacing
`&[rel_path.clone()]` with `std::slice::from_ref(&rel_path)` in
`handlers::video::generate_video` to avoid the alloc + clone for a
single-element slice.

All 707 tests still pass.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/hls_stats.rs

@@ -256,15 +256,14 @@ pub async fn hls_stats_handler(
 
     // Synchronous file IO + DB query — run on a blocking pool so the
     // actix worker thread stays free for other requests.
-    let stats = match web::block(move || compute_and_publish(&libraries, &exif_dao, &video_dir))
-        .await
-    {
-        Ok(s) => s,
-        Err(e) => {
-            warn!("/hls/stats: blocking task failed: {:?}", e);
-            Vec::new()
-        }
-    };
+    let stats =
+        match web::block(move || compute_and_publish(&libraries, &exif_dao, &video_dir)).await {
+            Ok(s) => s,
+            Err(e) => {
+                warn!("/hls/stats: blocking task failed: {:?}", e);
+                Vec::new()
+            }
+        };
 
     let total: usize = stats.iter().map(|s| s.total).sum();
     let with_playlist: usize = stats.iter().map(|s| s.with_playlist).sum();