feat(backend): add organization slugs

apps/backend/internal/organization/slug.go

@@ -0,0 +1,34 @@
+package organization
+
+import (
+	"errors"
+	"regexp"
+	"strings"
+)
+
+const (
+	slugMinLength = 1
+	slugMaxLength = 63
+)
+
+var (
+	slugPattern  = regexp.MustCompile(`^[a-z0-9]+(?:-[a-z0-9]+)*$`)
+	reservedSlug = "my"
+)
+
+var ErrInvalidSlug = errors.New("invalid organization slug")
+
+// NormalizeSlug lowercases and validates an organization slug.
+func NormalizeSlug(input string) (string, error) {
+	slug := strings.ToLower(strings.TrimSpace(input))
+	if len(slug) < slugMinLength || len(slug) > slugMaxLength {
+		return "", ErrInvalidSlug
+	}
+	if slug == reservedSlug {
+		return "", ErrInvalidSlug
+	}
+	if !slugPattern.MatchString(slug) {
+		return "", ErrInvalidSlug
+	}
+	return slug, nil
+}