fix(lint): reflect.Ptr -> reflect.Pointer, unblocking task check

`task check` has been red at HEAD since 2bb1fef adopted the canonical
.golangci.yml from infra/ci-templates, which enables govet's `inline` analyzer.
Nothing to do with the change it blocks; reproduced against a clean HEAD before
touching it.

reflect.Ptr is the pre-Go-1.18 spelling of reflect.Pointer and is a deprecated
alias for it. Identical constant, no behaviour change.

Separate commit because it is unrelated to the auth work that found it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

internal/tools/tool.go

@@ -36,7 +36,7 @@ func parseArgs(raw json.RawMessage, dst any) error {
 // allowlist check. Returns a typed ErrValidation naming the missing field.
 func validateRequiredIdentifiers(dst any) error {
 	v := reflect.ValueOf(dst)
-	if v.Kind() != reflect.Ptr || v.IsNil() {
+	if v.Kind() != reflect.Pointer || v.IsNil() {
 		return nil
 	}
 	v = v.Elem()