enable clippy pedantic for nova-stats, fix all warnings

stats-daemon/src/main.rs

@@ -55,8 +55,8 @@ fn main() {
         tick += 1;
 
         let elapsed = t0.elapsed();
-        if elapsed < interval {
-            thread::sleep(interval - elapsed);
+        if let Some(remaining) = interval.checked_sub(elapsed) {
+            thread::sleep(remaining);
         }
     }
 }