Use golangci-lint fmt to format code (#163)

Use `golangci-lint fmt` to format code, upgrading `.golangci.yml` to v2 and mirroring the linter configuration used by https://github.com/go-gitea/gitea. `gci` now handles import ordering into standard, project-local, blank, and default groups.

Mirrors https://github.com/go-gitea/gitea/pull/37194.

Changes:
- Upgrade `.golangci.yml` to v2 format with the same linter set as gitea (minus `prealloc`, `unparam`, `testifylint`, `nilnil` which produced too many pre-existing issues)
- Add path-based exclusions (`bodyclose`, `gosec` in tests; `gosec:G115`/`G117` globally)
- Run lint via `make lint-go` in CI instead of `golangci/golangci-lint-action`, matching the pattern used by other Gitea repos
- Apply safe auto-fixes (`modernize`, `perfsprint`, `usetesting`, etc.)
- Add explanations to existing `//nolint` directives
- Remove dead code (unused `newRemoteReusableWorkflow` and `networkName`), duplicate imports, and shadowed `max` builtins
- Replace deprecated `docker/distribution/reference` with `distribution/reference`
- Fix `Deprecated:` comment casing and simplify nil/len checks

---
This PR was written with the help of Claude Opus 4.7

Reviewed-on: https://gitea.com/gitea/act/pulls/163
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: silverwind <me@silverwind.io>
Co-committed-by: silverwind <me@silverwind.io>

pkg/common/executor_max_parallel_test.go

@@ -14,24 +14,24 @@ import (
 func TestMaxParallel2Quick(t *testing.T) {
 	ctx := context.Background()
 
-	var currentRunning int32
-	var maxSimultaneous int32
+	var currentRunning atomic.Int32
+	var maxSimultaneous atomic.Int32
 
 	executors := make([]Executor, 4)
-	for i := 0; i < 4; i++ {
+	for i := range 4 {
 		executors[i] = func(ctx context.Context) error {
-			current := atomic.AddInt32(&currentRunning, 1)
+			current := currentRunning.Add(1)
 
 			// Update max if needed
 			for {
-				maxValue := atomic.LoadInt32(&maxSimultaneous)
-				if current <= maxValue || atomic.CompareAndSwapInt32(&maxSimultaneous, maxValue, current) {
+				maxValue := maxSimultaneous.Load()
+				if current <= maxValue || maxSimultaneous.CompareAndSwap(maxValue, current) {
 					break
 				}
 			}
 
 			time.Sleep(10 * time.Millisecond)
-			atomic.AddInt32(&currentRunning, -1)
+			currentRunning.Add(-1)
 			return nil
 		}
 	}
@@ -39,7 +39,7 @@ func TestMaxParallel2Quick(t *testing.T) {
 	err := NewParallelExecutor(2, executors...)(ctx)
 
 	assert.NoError(t, err)
-	assert.LessOrEqual(t, atomic.LoadInt32(&maxSimultaneous), int32(2),
+	assert.LessOrEqual(t, maxSimultaneous.Load(), int32(2),
 		"Should not exceed max-parallel: 2")
 }
 
@@ -47,16 +47,16 @@ func TestMaxParallel2Quick(t *testing.T) {
 func TestMaxParallel1Sequential(t *testing.T) {
 	ctx := context.Background()
 
-	var currentRunning int32
-	var maxSimultaneous int32
+	var currentRunning atomic.Int32
+	var maxSimultaneous atomic.Int32
 	var executionOrder []int
 	var orderMutex sync.Mutex
 
 	executors := make([]Executor, 5)
-	for i := 0; i < 5; i++ {
+	for i := range 5 {
 		taskID := i
 		executors[i] = func(ctx context.Context) error {
-			current := atomic.AddInt32(&currentRunning, 1)
+			current := currentRunning.Add(1)
 
 			// Track execution order
 			orderMutex.Lock()
@@ -65,14 +65,14 @@ func TestMaxParallel1Sequential(t *testing.T) {
 
 			// Update max if needed
 			for {
-				maxValue := atomic.LoadInt32(&maxSimultaneous)
-				if current <= maxValue || atomic.CompareAndSwapInt32(&maxSimultaneous, maxValue, current) {
+				maxValue := maxSimultaneous.Load()
+				if current <= maxValue || maxSimultaneous.CompareAndSwap(maxValue, current) {
 					break
 				}
 			}
 
 			time.Sleep(20 * time.Millisecond)
-			atomic.AddInt32(&currentRunning, -1)
+			currentRunning.Add(-1)
 			return nil
 		}
 	}
@@ -80,7 +80,7 @@ func TestMaxParallel1Sequential(t *testing.T) {
 	err := NewParallelExecutor(1, executors...)(ctx)
 
 	assert.NoError(t, err)
-	assert.Equal(t, int32(1), atomic.LoadInt32(&maxSimultaneous),
+	assert.Equal(t, int32(1), maxSimultaneous.Load(),
 		"max-parallel: 1 should only run 1 task at a time")
 	assert.Len(t, executionOrder, 5, "All 5 tasks should have executed")
 }