Enhancement: Empty config

When user starts kportal for the first time, and there is no config file,
kportal should create an empty config file with default values and empty
forwarding rules, so that user can easily edit the config file and add their
own rules.

internal/config/validator_test.go

@@ -972,3 +972,141 @@ func TestIsAlphanumeric(t *testing.T) {
 		})
 	}
 }
+
+func TestValidator_ValidateConfigWithOptions(t *testing.T) {
+	validator := NewValidator()
+
+	tests := []struct {
+		name         string
+		config       *Config
+		allowEmpty   bool
+		expectErrors bool
+	}{
+		{
+			name:         "empty config - strict mode",
+			config:       &Config{Contexts: []Context{}},
+			allowEmpty:   false,
+			expectErrors: true,
+		},
+		{
+			name:         "empty config - allow empty",
+			config:       &Config{Contexts: []Context{}},
+			allowEmpty:   true,
+			expectErrors: false,
+		},
+		{
+			name:         "nil contexts - allow empty",
+			config:       &Config{},
+			allowEmpty:   true,
+			expectErrors: false,
+		},
+		{
+			name: "context with no forwards - allow empty",
+			config: &Config{
+				Contexts: []Context{
+					{
+						Name: "dev",
+						Namespaces: []Namespace{
+							{Name: "default", Forwards: []Forward{}},
+						},
+					},
+				},
+			},
+			allowEmpty:   true,
+			expectErrors: false,
+		},
+		{
+			name: "valid config - strict mode",
+			config: &Config{
+				Contexts: []Context{
+					{
+						Name: "dev-cluster",
+						Namespaces: []Namespace{
+							{
+								Name: "default",
+								Forwards: []Forward{
+									{
+										Resource:      "pod/my-app",
+										Protocol:      "tcp",
+										Port:          8080,
+										LocalPort:     8080,
+										contextName:   "dev-cluster",
+										namespaceName: "default",
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+			allowEmpty:   false,
+			expectErrors: false,
+		},
+		{
+			name: "valid config - allow empty (should still validate)",
+			config: &Config{
+				Contexts: []Context{
+					{
+						Name: "dev-cluster",
+						Namespaces: []Namespace{
+							{
+								Name: "default",
+								Forwards: []Forward{
+									{
+										Resource:      "pod/my-app",
+										Protocol:      "tcp",
+										Port:          8080,
+										LocalPort:     8080,
+										contextName:   "dev-cluster",
+										namespaceName: "default",
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+			allowEmpty:   true,
+			expectErrors: false,
+		},
+		{
+			name: "invalid forward in non-empty config - allow empty still validates",
+			config: &Config{
+				Contexts: []Context{
+					{
+						Name: "dev-cluster",
+						Namespaces: []Namespace{
+							{
+								Name: "default",
+								Forwards: []Forward{
+									{
+										Resource:      "pod/my-app",
+										Protocol:      "tcp",
+										Port:          0, // Invalid port
+										LocalPort:     8080,
+										contextName:   "dev-cluster",
+										namespaceName: "default",
+									},
+								},
+							},
+						},
+					},
+				},
+			},
+			allowEmpty:   true,
+			expectErrors: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			errs := validator.ValidateConfigWithOptions(tt.config, tt.allowEmpty)
+
+			if tt.expectErrors {
+				assert.NotEmpty(t, errs, "expected validation errors")
+			} else {
+				assert.Empty(t, errs, "expected no validation errors, got: %v", errs)
+			}
+		})
+	}
+}