feat: LokiDeploy 初始提交 - 轻量级 K8s Loki 部署平台

Go(Gin) + React(Vite + shadcn/ui + Tailwind) 前后端分离，全中文 UI

- 集群管理：Kubeconfig / Token 双接入，kubectl + helm 部署
- 主机管理：SSH 密钥 / 密码双认证，CPU/内存/磁盘使用率监控，SSH 错误中文友好提示
- 存储配置、部署管理、系统设置
- Docker 镜像内置 kubectl + helm，开箱即用
- run.sh 一键启停（start/stop/restart/status）

Co-Authored-By: Claude <noreply@anthropic.com>

backend/services/k8s_client.go

@@ -0,0 +1,58 @@
+package services
+
+import (
+	"fmt"
+	"os"
+	"regexp"
+
+	"lokideploy/models"
+)
+
+// resolveKubeconfig 取集群最终的 kubeconfig 文本（优先内存字段，其次磁盘文件）
+func resolveKubeconfig(cluster *models.Cluster) (string, error) {
+	if cluster.KubeConfig != "" {
+		return cluster.KubeConfig, nil
+	}
+	if cluster.KubeConfigPath != "" {
+		data, err := os.ReadFile(cluster.KubeConfigPath)
+		if err != nil {
+			return "", fmt.Errorf("读取 kubeconfig 文件失败: %v", err)
+		}
+		return string(data), nil
+	}
+	return "", fmt.Errorf("集群未配置 kubeconfig")
+}
+
+// BuildKubeconfigFromToken 用 API Server + Token 构造最小 kubeconfig
+// 采用 insecure-skip-tls-verify，便于内网/自签证书集群接入
+func BuildKubeconfigFromToken(apiServer, token string) string {
+	return fmt.Sprintf(`apiVersion: v1
+kind: Config
+clusters:
+- cluster:
+    insecure-skip-tls-verify: true
+    server: %s
+  name: loki-cluster
+contexts:
+- context:
+    cluster: loki-cluster
+    user: loki-user
+  name: loki-context
+current-context: loki-context
+users:
+- name: loki-user
+  user:
+    token: %s
+`, apiServer, token)
+}
+
+var apiServerRe = regexp.MustCompile(`(?m)^\s*server:\s*(\S+)`)
+
+// ExtractAPIServer 从 kubeconfig 文本提取 server 地址（展示用）
+func ExtractAPIServer(kubeconfig string) string {
+	m := apiServerRe.FindStringSubmatch(kubeconfig)
+	if len(m) >= 2 {
+		return m[1]
+	}
+	return ""
+}