feat(kol): add KOL profile field validators

server/internal/tenant/app/kol_profile_validate.go

@@ -0,0 +1,53 @@
+package app
+
+import (
+	"strings"
+	"unicode/utf8"
+
+	"github.com/geo-platform/tenant-api/internal/shared/response"
+)
+
+const (
+	kolDisplayNameMaxLen = 40
+	kolBioMaxLen         = 500
+	kolAvatarURLPrefix   = "/api/public/assets/"
+)
+
+func validateKolDisplayName(raw string) (string, error) {
+	v := strings.TrimSpace(raw)
+	if v == "" {
+		return "", response.ErrBadRequest(40001, "kol_profile_invalid_display_name", "display_name is required")
+	}
+	if utf8.RuneCountInString(v) > kolDisplayNameMaxLen {
+		return "", response.ErrBadRequest(40001, "kol_profile_invalid_display_name", "display_name must be at most 40 characters")
+	}
+	return v, nil
+}
+
+func validateKolBio(raw *string) (*string, error) {
+	if raw == nil {
+		return nil, nil
+	}
+	v := strings.TrimSpace(*raw)
+	if v == "" {
+		return nil, nil
+	}
+	if utf8.RuneCountInString(v) > kolBioMaxLen {
+		return nil, response.ErrBadRequest(40002, "kol_profile_invalid_bio", "bio must be at most 500 characters")
+	}
+	return &v, nil
+}
+
+func validateKolAvatarURL(raw *string) (*string, error) {
+	if raw == nil {
+		return nil, nil
+	}
+	v := strings.TrimSpace(*raw)
+	if v == "" {
+		return nil, nil
+	}
+	if !strings.HasPrefix(v, kolAvatarURLPrefix) {
+		return nil, response.ErrBadRequest(40003, "kol_profile_invalid_avatar_url", "avatar_url must be an asset path served by this service")
+	}
+	return &v, nil
+}