fix: harden ops runbooks and execution

internal/core/runbook/targets.go

@@ -0,0 +1,37 @@
+package runbook
+
+import (
+	"strings"
+
+	"ops-assistant/models"
+
+	"gorm.io/gorm"
+)
+
+type ResolvedTarget struct {
+	Found bool
+	User  string
+	Host  string
+	Port  int
+}
+
+func resolveTarget(db *gorm.DB, name string) ResolvedTarget {
+	trim := strings.TrimSpace(name)
+	if trim == "" {
+		return ResolvedTarget{}
+	}
+	var t models.OpsTarget
+	if err := db.Where("name = ? AND enabled = ?", trim, true).First(&t).Error; err != nil {
+		return ResolvedTarget{}
+	}
+	user := strings.TrimSpace(t.User)
+	host := strings.TrimSpace(t.Host)
+	port := t.Port
+	if user == "" || host == "" {
+		return ResolvedTarget{}
+	}
+	if port <= 0 {
+		port = 22
+	}
+	return ResolvedTarget{Found: true, User: user, Host: host, Port: port}
+}