feat(k3s): add node taints configuration and update documentation

ansible/README.md

@@ -98,6 +98,31 @@ kubectl get nodes
 | `enable_lb` | bool | - | 启用 K3s LB |
 | `netfilter_mode` | string | "" | Tailscale netfilter: off/nodivert/on |
 | `node_labels` | dict | - | 自定义标签 |
+| `node_taints` | list | - | 节点污点 (格式: key=value:effect) |
+
+### 节点污点示例
+
+```yaml
+masters:
+  hosts:
+    master1:
+      ansible_host: 10.0.0.1
+      node_taints:
+        - "node-role.kubernetes.io/control-plane:NoSchedule"
+        - "dedicated=gpu:NoSchedule"
+
+agents:
+  hosts:
+    gpu-node:
+      ansible_host: 10.0.0.10
+      node_taints:
+        - "nvidia.com/gpu:NoSchedule"
+```
+
+常用污点效果（Effect）：
+- **NoSchedule**: 不允许新 Pod 调度到此节点
+- **PreferNoSchedule**: 尽量不调度（软限制）
+- **NoExecute**: 驱逐已有 Pod 并禁止新 Pod
 | `kubelet_reserved` | string | - | 资源预留: cpu=500m,memory=512Mi |
 
 ## 环境变量