Add k3s cluster expansion documentation and scripts

- Complete expansion guide for 2/4/6 node scenarios
- Quick join scripts for worker and master nodes
- Health check and diagnostic scripts
- Quick reference card for common operations

k3s/my-blog/02-wordpress.yaml

@@ -5,6 +5,10 @@ metadata:
   name: wordpress-service
   namespace: demo-space
 spec:
+  sessionAffinity: ClientIP
+  sessionAffinityConfig:
+    clientIP:
+      timeoutSeconds: 10800  # 3 hours
   ports:
   - port: 80
   selector:
@@ -48,6 +52,9 @@ spec:
             }
             /* Force SSL for admin */
             define('FORCE_SSL_ADMIN', true);
+            /* Redis session storage for multi-replica support */
+            @ini_set('session.save_handler', 'redis');
+            @ini_set('session.save_path', 'tcp://redis-service:6379');
             /* Fix cookie issues */
             @ini_set('session.cookie_httponly', true);
             @ini_set('session.cookie_secure', true);