feat: replace mapping generation with checked copy utilities

examples/copying/main.go

@@ -0,0 +1,61 @@
+// copying demonstrates optional Go-to-Go conversion and checked deep copying.
+package main
+
+import (
+	"errors"
+	"fmt"
+	"log"
+	"time"
+
+	"git.yuntuo.hk/k2safe/go-omni/copyx"
+)
+
+type Input struct {
+	Name      string
+	Enabled   bool
+	Tags      []string
+	CreatedAt time.Time
+}
+type View struct {
+	DisplayName string
+	Enabled     bool
+	Tags        []string
+	CreatedAt   string
+}
+
+func run() error {
+	converter, err := copyx.New(
+		copyx.WithDeepCopy(),
+		copyx.WithFieldNames[Input, View](map[string]string{"Name": "DisplayName"}),
+		copyx.WithConverter(func(v time.Time) (string, error) { return v.UTC().Format(time.RFC3339), nil }),
+	)
+	if err != nil {
+		return err
+	}
+	source := Input{Name: "sample", Enabled: false, Tags: []string{"original"}, CreatedAt: time.Date(2026, 1, 1, 0, 0, 0, 0, time.UTC)}
+	var target View
+	if err = converter.Copy(&target, source); err != nil {
+		return err
+	}
+	target.Tags[0] = "changed"
+	fmt.Printf("name=%s enabled=%t time=%s sourceTag=%s\n", target.DisplayName, target.Enabled, target.CreatedAt, source.Tags[0])
+
+	cloned, err := copyx.Clone(source)
+	if err != nil {
+		return err
+	}
+	cloned.Tags[0] = "separate"
+	fmt.Println("clone detached:", source.Tags[0] == "original")
+
+	_, err = copyx.Clone(source.Tags, copyx.WithConverter(func(v []string) ([]string, error) { return v, nil }))
+	fmt.Println("shared converter rejected:", errors.Is(err, copyx.ErrSharedReference))
+	if !errors.Is(err, copyx.ErrSharedReference) {
+		return errors.New("expected alias rejection")
+	}
+	return nil
+}
+func main() {
+	if err := run(); err != nil {
+		log.Fatal(err)
+	}
+}