Add cleanup stack

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

internal/cleanup/cleanup.go

@@ -0,0 +1,24 @@
+package cleanup
+
+// Stack holds deferred cleanup functions and runs them in LIFO order.
+// Errors are collected; one cleanup failure does not stop later ones.
+type Stack struct {
+	fns []func() error
+}
+
+// Add registers fn to run on Run().
+func (s *Stack) Add(fn func() error) {
+	s.fns = append(s.fns, fn)
+}
+
+// Run executes all registered functions in reverse order and returns
+// every error produced.
+func (s *Stack) Run() []error {
+	var errs []error
+	for i := len(s.fns) - 1; i >= 0; i-- {
+		if err := s.fns[i](); err != nil {
+			errs = append(errs, err)
+		}
+	}
+	return errs
+}

internal/cleanup/cleanup_test.go

@@ -0,0 +1,42 @@
+package cleanup_test
+
+import (
+	"errors"
+	"strings"
+	"testing"
+
+	"github.com/leonmika/wails-release/internal/cleanup"
+)
+
+func TestStack_RunsInReverseOrder(t *testing.T) {
+	var s cleanup.Stack
+	calls := []string{}
+	s.Add(func() error { calls = append(calls, "first"); return nil })
+	s.Add(func() error { calls = append(calls, "second"); return nil })
+
+	s.Run()
+
+	want := []string{"second", "first"}
+	for i := range want {
+		if calls[i] != want[i] {
+			t.Fatalf("call %d: got %q want %q (full: %v)", i, calls[i], want[i], calls)
+		}
+	}
+}
+
+func TestStack_ContinuesAfterError(t *testing.T) {
+	var s cleanup.Stack
+	called := []string{}
+	s.Add(func() error { called = append(called, "a"); return nil })
+	s.Add(func() error { called = append(called, "b"); return errors.New("boom") })
+	s.Add(func() error { called = append(called, "c"); return nil })
+
+	errs := s.Run()
+
+	if len(errs) != 1 || !strings.Contains(errs[0].Error(), "boom") {
+		t.Fatalf("expected one boom error, got %v", errs)
+	}
+	if len(called) != 3 {
+		t.Fatalf("expected all three to run, got %v", called)
+	}
+}