fix: prevent EADDRINUSE double-bind on Holesail client startup

Add global activeClientKeys Set to track all active clients and prevent
race conditions between domain init and cache restore paths. Add EADDRINUSE
error handling in holesail.js, holesail_child.js

includes/infrastructure/state.js

@@ -97,5 +97,7 @@ module.exports = {
     // Pending invite requests queue for when master isn't ready
     pendingInviteRequests: new Map(), // Map<peerId, {timestamp, retryCount}>
     // Shutdown flag to prevent operations during cleanup
-    isShuttingDown: false
+    isShuttingDown: false,
+    // Global set to track all active client keys (both forked and direct) to prevent double-bind
+    activeClientKeys: new Set()
 };