feat: add repository pattern, service layer architecture, and scheduler management

- Implement repository pattern for data access layer
- Add comprehensive service layer for business logic
- Create scheduler management system with health monitoring
- Add bounded buffer utility for memory management
- Enhance security audit logging with retention policies

app/api/admin/schedulers/health/route.ts

@@ -0,0 +1,61 @@
+import { NextResponse } from "next/server";
+import { getSchedulerIntegration } from "@/lib/services/schedulers/ServerSchedulerIntegration";
+
+/**
+ * Health check endpoint for schedulers
+ * Used by load balancers and orchestrators for health monitoring
+ */
+export async function GET() {
+  try {
+    const integration = getSchedulerIntegration();
+    const health = integration.getHealthStatus();
+
+    // Return appropriate HTTP status based on health
+    const status = health.healthy ? 200 : 503;
+
+    return NextResponse.json(
+      {
+        healthy: health.healthy,
+        status: health.healthy ? "healthy" : "unhealthy",
+        timestamp: new Date().toISOString(),
+        schedulers: {
+          total: health.totalSchedulers,
+          running: health.runningSchedulers,
+          errors: health.errorSchedulers,
+        },
+        details: health.schedulerStatuses,
+      },
+      { status }
+    );
+  } catch (error) {
+    console.error("[Scheduler Health API] Error:", error);
+
+    return NextResponse.json(
+      {
+        healthy: false,
+        status: "error",
+        timestamp: new Date().toISOString(),
+        error: "Failed to get scheduler health status",
+      },
+      { status: 500 }
+    );
+  }
+}
+
+/**
+ * Readiness check endpoint
+ * Used by Kubernetes and other orchestrators
+ */
+export async function HEAD() {
+  try {
+    const integration = getSchedulerIntegration();
+    const health = integration.getHealthStatus();
+
+    // Return 200 if healthy, 503 if not
+    const status = health.healthy ? 200 : 503;
+
+    return new NextResponse(null, { status });
+  } catch (_error) {
+    return new NextResponse(null, { status: 500 });
+  }
+}