fix(scanner): respect configured scan start delay (#2119)

crates/scanner/src/sleeper.rs

@@ -137,6 +137,7 @@ impl SleepTimer {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use serial_test::serial;
 
     #[test]
     fn test_scanner_speed_presets() {
@@ -166,6 +167,7 @@ mod tests {
     }
 
     #[tokio::test(start_paused = true)]
+    #[serial]
     async fn test_fastest_never_sleeps() {
         let prev_mode = SCANNER_IDLE_MODE.load(Ordering::Relaxed);
         SCANNER_IDLE_MODE.store(true, Ordering::Relaxed);
@@ -179,6 +181,7 @@ mod tests {
     }
 
     #[tokio::test(start_paused = true)]
+    #[serial]
     async fn test_idle_mode_off_skips_sleep() {
         let prev_mode = SCANNER_IDLE_MODE.load(Ordering::Relaxed);
         SCANNER_IDLE_MODE.store(false, Ordering::Relaxed);