feat(FN-1079): add remote node runtime orchestration

- Add RemoteNodeClient and RemoteNodeRuntime with comprehensive lifecycle, status, and metrics test coverage
- Route projects by node assignment in ProjectManager and integrate remote runtime handling in HybridExecutor
- Introduce NodeHealthMonitor and wire diagnostic logging/export updates for remote node health tracking
- Harden remote runtime shutdown checks and type-safety paths surfaced during review feedback

packages/engine/src/hybrid-executor.ts

@@ -1,6 +1,7 @@
 import { EventEmitter } from "node:events";
 import type { Task, CentralCore, RegisteredProject } from "@fusion/core";
 import { ProjectManager } from "./project-manager.js";
+import { NodeHealthMonitor } from "./node-health-monitor.js";
 import type {
   ProjectRuntime,
   ProjectRuntimeConfig,
@@ -133,6 +134,7 @@ export interface HybridExecutorOptions {
  */
 export class HybridExecutor extends EventEmitter<HybridExecutorEvents> {
   private projectManager: ProjectManager;
+  private nodeHealthMonitor: NodeHealthMonitor | null = null;
   private initialized = false;
 
   /**
@@ -197,6 +199,10 @@ export class HybridExecutor extends EventEmitter<HybridExecutorEvents> {
     // Listen for CentralCore project events
     this.setupCentralCoreListeners();
 
+    // Start remote node health monitoring after project runtimes are loaded.
+    this.nodeHealthMonitor = new NodeHealthMonitor(this.centralCore);
+    await this.nodeHealthMonitor.start();
+
     this.initialized = true;
     hybridExecutorLog.log("HybridExecutor initialized");
   }
@@ -318,6 +324,13 @@ export class HybridExecutor extends EventEmitter<HybridExecutorEvents> {
     return this.projectManager.getGlobalMetrics();
   }
 
+  /**
+   * Get the optional node health monitor instance.
+   */
+  getNodeHealthMonitor(): NodeHealthMonitor | null {
+    return this.nodeHealthMonitor;
+  }
+
   /**
    * Acquire a global concurrency slot.
    *
@@ -355,6 +368,12 @@ export class HybridExecutor extends EventEmitter<HybridExecutorEvents> {
     this.centralCore.removeAllListeners("project:unregistered");
     this.centralCore.removeAllListeners("project:updated");
 
+    // Stop node health monitor before shutting down runtimes.
+    if (this.nodeHealthMonitor) {
+      await this.nodeHealthMonitor.stop();
+      this.nodeHealthMonitor = null;
+    }
+
     // Stop all runtimes
     await this.projectManager.stopAll();