chore(lint): add golangci-lint v2 and fix all lint issues (#803)

## Summary
- Replace old `.golangci.yml` (v1 format) with v2 format, aligned with gitea's lint config
- Add `lint-go`, `lint-go-fix`, and `lint` Makefile targets using golangci-lint v2.10.1
- Replace `make vet` with `make lint` in CI workflow (lint includes vet)
- Fix all 35 lint issues: modernize (maps.Copy, range over int, any), perfsprint (errors.New), unparam (remove unused parameters), revive (var naming), staticcheck, forbidigo exclusion for cmd/
- Make `security-check` non-fatal (apply https://github.com/go-gitea/gitea/pull/36681)
- Remove dead gocritic exclusion rules (commentFormatting, exitAfterDefer)
- Remove dead linter exclusions and disabled checks (singleCaseSwitch, ST1003, QF1001, QF1006, QF1008, testifylint go-require/require-error, test file exclusions for dupl/errcheck/staticcheck/unparam)

## Test plan
- [x] `golangci-lint run` passes
- [x] `go build ./...` passes
- [x] `go test ./...` passes

---------

Co-authored-by: ChristopherHX <christopher.homberger@web.de>
Co-authored-by: Christopher Homberger <christopher.homberger@web.de>
Reviewed-on: https://gitea.com/gitea/act_runner/pulls/803
Reviewed-by: ChristopherHX <christopherhx@noreply.gitea.com>

internal/app/cmd/cache-server.go

@@ -4,7 +4,6 @@
 package cmd
 
 import (
-	"context"
 	"fmt"
 	"os"
 	"os/signal"
@@ -22,7 +21,7 @@ type cacheServerArgs struct {
 	Port uint16
 }
 
-func runCacheServer(ctx context.Context, configFile *string, cacheArgs *cacheServerArgs) func(cmd *cobra.Command, args []string) error {
+func runCacheServer(configFile *string, cacheArgs *cacheServerArgs) func(cmd *cobra.Command, args []string) error {
 	return func(cmd *cobra.Command, args []string) error {
 		cfg, err := config.LoadDefault(*configFile)
 		if err != nil {

internal/app/cmd/cmd.go

@@ -72,7 +72,7 @@ func Execute(ctx context.Context) {
 		Use:   "cache-server",
 		Short: "Start a cache server for the cache action",
 		Args:  cobra.MaximumNArgs(0),
-		RunE:  runCacheServer(ctx, &configFile, &cacheArgs),
+		RunE:  runCacheServer(&configFile, &cacheArgs),
 	}
 	cacheCmd.Flags().StringVarP(&cacheArgs.Dir, "dir", "d", "", "Cache directory")
 	cacheCmd.Flags().StringVarP(&cacheArgs.Host, "host", "s", "", "Host of the cache server")

internal/app/cmd/daemon.go

@@ -262,5 +262,5 @@ func getDockerSocketPath(configDockerHost string) (string, error) {
 		}
 	}
 
-	return "", fmt.Errorf("daemon Docker Engine socket not found and docker_host config was invalid")
+	return "", errors.New("daemon Docker Engine socket not found and docker_host config was invalid")
 }

internal/app/cmd/exec.go

@@ -6,7 +6,9 @@ package cmd
 
 import (
 	"context"
+	"errors"
 	"fmt"
+	"maps"
 	"os"
 	"path/filepath"
 	"strconv"
@@ -77,7 +79,7 @@ func (i *executeArgs) LoadSecrets() map[string]string {
 	for _, secretPair := range i.secrets {
 		secretPairParts := strings.SplitN(secretPair, "=", 2)
 		secretPairParts[0] = strings.ToUpper(secretPairParts[0])
-		if strings.ToUpper(s[secretPairParts[0]]) == secretPairParts[0] {
+		if strings.EqualFold(s[secretPairParts[0]], secretPairParts[0]) {
 			log.Errorf("Secret %s is already defined (secrets are case insensitive)", secretPairParts[0])
 		}
 		if len(secretPairParts) == 2 {
@@ -104,9 +106,7 @@ func readEnvs(path string, envs map[string]string) bool {
 		if err != nil {
 			log.Fatalf("Error loading from %s: %v", path, err)
 		}
-		for k, v := range env {
-			envs[k] = v
-		}
+		maps.Copy(envs, env)
 		return true
 	}
 	return false
@@ -166,7 +166,7 @@ func (i *executeArgs) resolve(path string) string {
 	return path
 }
 
-func printList(plan *model.Plan) error {
+func printList(plan *model.Plan) {
 	type lineInfoDef struct {
 		jobID   string
 		jobName string
@@ -261,10 +261,9 @@ func printList(plan *model.Plan) error {
 	if duplicateJobIDs {
 		fmt.Print("\nDetected multiple jobs with the same job name, use `-W` to specify the path to the specific workflow.\n")
 	}
-	return nil
 }
 
-func runExecList(ctx context.Context, planner model.WorkflowPlanner, execArgs *executeArgs) error {
+func runExecList(planner model.WorkflowPlanner, execArgs *executeArgs) error {
 	// plan with filtered jobs - to be used for filtering only
 	var filterPlan *model.Plan
 
@@ -306,7 +305,7 @@ func runExecList(ctx context.Context, planner model.WorkflowPlanner, execArgs *e
 		}
 	}
 
-	_ = printList(filterPlan)
+	printList(filterPlan)
 
 	return nil
 }
@@ -319,7 +318,7 @@ func runExec(ctx context.Context, execArgs *executeArgs) func(cmd *cobra.Command
 		}
 
 		if execArgs.runList {
-			return runExecList(ctx, planner, execArgs)
+			return runExecList(planner, execArgs)
 		}
 
 		// plan with triggered jobs
@@ -378,7 +377,7 @@ func runExec(ctx context.Context, execArgs *executeArgs) func(cmd *cobra.Command
 		if len(execArgs.artifactServerAddr) == 0 {
 			ip := common.GetOutboundIP()
 			if ip == nil {
-				return fmt.Errorf("unable to determine outbound IP address")
+				return errors.New("unable to determine outbound IP address")
 			}
 			execArgs.artifactServerAddr = ip.String()
 		}
@@ -422,7 +421,7 @@ func runExec(ctx context.Context, execArgs *executeArgs) func(cmd *cobra.Command
 			NoSkipCheckout:        execArgs.noSkipCheckout,
 			// PresetGitHubContext:   preset,
 			// EventJSON:             string(eventJSON),
-			ContainerNamePrefix:   fmt.Sprintf("GITEA-ACTIONS-TASK-%s", eventName),
+			ContainerNamePrefix:   "GITEA-ACTIONS-TASK-" + eventName,
 			ContainerMaxLifetime:  maxLifetime,
 			ContainerNetworkMode:  container.NetworkMode(execArgs.network),
 			DefaultActionInstance: execArgs.defaultActionsURL,

internal/app/cmd/register.go

@@ -6,6 +6,7 @@ package cmd
 import (
 	"bufio"
 	"context"
+	"errors"
 	"fmt"
 	"os"
 	"os/signal"
@@ -107,10 +108,10 @@ type registerInputs struct {
 
 func (r *registerInputs) validate() error {
 	if r.InstanceAddr == "" {
-		return fmt.Errorf("instance address is empty")
+		return errors.New("instance address is empty")
 	}
 	if r.Token == "" {
-		return fmt.Errorf("token is empty")
+		return errors.New("token is empty")
 	}
 	if len(r.Labels) > 0 {
 		return validateLabels(r.Labels)