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/runner/job_executor.go

@@ -3,6 +3,7 @@ package runner
 import (
 	"context"
 	"fmt"
+	"strconv"
 	"time"
 
 	"github.com/nektos/act/pkg/common"
@@ -10,7 +11,7 @@ import (
 )
 
 type jobInfo interface {
-	matrix() map[string]interface{}
+	matrix() map[string]any
 	steps() []*model.Step
 	startContainer() common.Executor
 	stopContainer() common.Executor
@@ -19,7 +20,7 @@ type jobInfo interface {
 	result(result string)
 }
 
-//nolint:contextcheck,gocyclo
+//nolint:contextcheck,gocyclo // composes many step executors
 func newJobExecutor(info jobInfo, sf stepFactory, rc *RunContext) common.Executor {
 	steps := make([]common.Executor, 0)
 	preSteps := make([]common.Executor, 0)
@@ -54,19 +55,17 @@ func newJobExecutor(info jobInfo, sf stepFactory, rc *RunContext) common.Executo
 	})
 
 	for i, stepModel := range infoSteps {
-		stepModel := stepModel
 		if stepModel == nil {
 			return func(ctx context.Context) error {
 				return fmt.Errorf("invalid Step %v: missing run or uses key", i)
 			}
 		}
 		if stepModel.ID == "" {
-			stepModel.ID = fmt.Sprintf("%d", i)
+			stepModel.ID = strconv.Itoa(i)
 		}
 		stepModel.Number = i
 
 		step, err := sf.newStep(stepModel, rc)
-
 		if err != nil {
 			return common.NewErrorExecutor(err)
 		}
@@ -154,7 +153,7 @@ func newJobExecutor(info jobInfo, sf stepFactory, rc *RunContext) common.Executo
 	pipeline = append(pipeline, steps...)
 
 	return common.NewPipelineExecutor(info.startContainer(), common.NewPipelineExecutor(pipeline...).
-		Finally(func(ctx context.Context) error { //nolint:contextcheck
+		Finally(func(ctx context.Context) error { //nolint:contextcheck // intentionally detaches from canceled parent
 			var cancel context.CancelFunc
 			if ctx.Err() == context.Canceled {
 				// in case of an aborted run, we still should execute the