perf: skip missed ticks on all intervals, reduce scan frequency

Prevents burst of health checks, scans, and snapshots after slow
podman responses by using MissedTickBehavior::Skip. Bumps container
scan interval from 30s to 60s to reduce DB lock contention.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

core/archipelago/src/server.rs

@@ -277,9 +277,12 @@ impl Server {
                     error!("Failed to scan containers: {}", e);
                 }
 
-                // Periodic scan every 30 seconds (only broadcasts if state changed)
+                // Periodic scan every 60 seconds (only broadcasts if state changed)
                 // Uses an in-flight guard to skip scans when a previous one is still running
-                let mut interval = tokio::time::interval(Duration::from_secs(30));
+                let mut interval = tokio::time::interval(Duration::from_secs(60));
+                // Skip missed ticks instead of catching up — prevents burst of scans
+                // after a slow podman response (which causes DB lock storms)
+                interval.set_missed_tick_behavior(tokio::time::MissedTickBehavior::Skip);
                 let scanning = std::sync::Arc::new(std::sync::atomic::AtomicBool::new(false));
                 loop {
                     interval.tick().await;