feat(health-check): introduce health probe gap configuration and enhance health check logic

Added `healthProbeGapMs` configuration to control the minimum pause between probes to different physical targets. Updated health check service to utilize this configuration, ensuring efficient probing without overwhelming the targets. Enhanced the `runAllChecks` function to group probes by physical IP and implement the new gap logic. Updated related tests to validate the new functionality.

packages/db/src/repos.ts

@@ -1687,6 +1687,38 @@ export function deleteIpHealthStatusForIp(
     .run();
 }
 
+/** Drop health rows whose IP is no longer a live probe target for that scope/ref. */
+export function pruneStaleIpHealthStatus(
+  db: Db,
+  activeTargets: Array<{ scope: HealthCheckScope; ref_id: number; ip: string }>,
+): number {
+  const byRef = new Map<string, Set<string>>();
+  for (const t of activeTargets) {
+    const key = `${t.scope}:${t.ref_id}`;
+    let ips = byRef.get(key);
+    if (!ips) {
+      ips = new Set();
+      byRef.set(key, ips);
+    }
+    ips.add(t.ip);
+  }
+
+  let deleted = 0;
+  for (const [key, ips] of byRef) {
+    const sep = key.indexOf(":");
+    const scope = key.slice(0, sep) as HealthCheckScope;
+    const refId = Number(key.slice(sep + 1));
+    if (!Number.isFinite(refId)) continue;
+    for (const row of listIpHealthStatus(db, scope, refId)) {
+      if (!ips.has(row.ip)) {
+        deleteIpHealthStatusForIp(db, scope, refId, row.ip);
+        deleted += 1;
+      }
+    }
+  }
+  return deleted;
+}
+
 // --- Health Check Targets ---
 
 export function listHealthCheckTargets(db: Db): HealthCheckTarget[] {