chore: clean up nolint directives in act package (#864)

Removes 88 `nolint` directives (386 → 298) via mechanical, zero-regression cleanups:

- **38 `bodyclose`** in `act/artifactcache/handler_test.go`: replaced by `defer resp.Body.Close()` after each HTTP call.
- **21 dead directives** (`gocyclo`, `dogsled`, `contextcheck`): none of these linters are enabled in `.golangci.yml`, so the directives were doing nothing.
- **29 `testifylint`** directives whose underlying issues were addressed by mechanical rewrites:
  - `assert.Nil(t, err)` → `assert.NoError(t, err)`
  - `assert.NotNil(t, err)` → `assert.Error(t, err)`
  - `assert.Equal(t, true/false, x)` → `assert.True/False(t, x)`
  - `assert.Equal(t, 0, len(x))` → `assert.Empty(t, x)`
  - `assert.Equal(t, N, len(x))` → `assert.Len(t, x, N)`
  - `assert.Len(t, x, 0)` → `assert.Empty(t, x)`

Many `testifylint` directives still apply because they flag `require-error` (i.e. testifylint wants `require.NoError` instead of `assert.NoError` for early bail-out). That's a behavior change (fail-fast vs continue) and out of scope for this purely mechanical cleanup — those can be addressed in a follow-up. Same for `expected-actual`, `equal-values`, `error-is-as`, and the remaining `nilnil` / `unparam` / `forbidigo` / `staticcheck` / `goheader` / `dupl` directives.

`golangci-lint run` is clean. Tests pass for all touched packages.

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

Reviewed-on: https://gitea.com/gitea/act_runner/pulls/864
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: silverwind <2021+silverwind@noreply.gitea.com>
Co-committed-by: silverwind <2021+silverwind@noreply.gitea.com>

act/container/docker_images_test.go

@@ -29,17 +29,17 @@ func TestImageExistsLocally(t *testing.T) {
 
 	// Test if image exists with specific tag
 	invalidImageTag, err := ImageExistsLocally(ctx, "library/alpine:this-random-tag-will-never-exist", "linux/amd64")
-	assert.Nil(t, err)                      //nolint:testifylint // pre-existing issue from nektos/act
-	assert.Equal(t, false, invalidImageTag) //nolint:testifylint // pre-existing issue from nektos/act
+	assert.NoError(t, err) //nolint:testifylint // pre-existing issue from nektos/act
+	assert.False(t, invalidImageTag)
 
 	// Test if image exists with specific architecture (image platform)
 	invalidImagePlatform, err := ImageExistsLocally(ctx, "alpine:latest", "windows/amd64")
-	assert.Nil(t, err)                           //nolint:testifylint // pre-existing issue from nektos/act
-	assert.Equal(t, false, invalidImagePlatform) //nolint:testifylint // pre-existing issue from nektos/act
+	assert.NoError(t, err) //nolint:testifylint // pre-existing issue from nektos/act
+	assert.False(t, invalidImagePlatform)
 
 	// pull an image
 	cli, err := client.NewClientWithOpts(client.FromEnv)
-	assert.Nil(t, err) //nolint:testifylint // pre-existing issue from nektos/act
+	assert.NoError(t, err) //nolint:testifylint // pre-existing issue from nektos/act
 	cli.NegotiateAPIVersion(context.Background())
 
 	// Chose alpine latest because it's so small
@@ -47,25 +47,25 @@ func TestImageExistsLocally(t *testing.T) {
 	readerDefault, err := cli.ImagePull(ctx, "node:16-buster-slim", types.ImagePullOptions{
 		Platform: "linux/amd64",
 	})
-	assert.Nil(t, err) //nolint:testifylint // pre-existing issue from nektos/act
+	assert.NoError(t, err) //nolint:testifylint // pre-existing issue from nektos/act
 	defer readerDefault.Close()
 	_, err = io.ReadAll(readerDefault)
-	assert.Nil(t, err) //nolint:testifylint // pre-existing issue from nektos/act
+	assert.NoError(t, err) //nolint:testifylint // pre-existing issue from nektos/act
 
 	imageDefaultArchExists, err := ImageExistsLocally(ctx, "node:16-buster-slim", "linux/amd64")
-	assert.Nil(t, err)                            //nolint:testifylint // pre-existing issue from nektos/act
-	assert.Equal(t, true, imageDefaultArchExists) //nolint:testifylint // pre-existing issue from nektos/act
+	assert.NoError(t, err) //nolint:testifylint // pre-existing issue from nektos/act
+	assert.True(t, imageDefaultArchExists)
 
 	// Validate if another architecture platform can be pulled
 	readerArm64, err := cli.ImagePull(ctx, "node:16-buster-slim", types.ImagePullOptions{
 		Platform: "linux/arm64",
 	})
-	assert.Nil(t, err) //nolint:testifylint // pre-existing issue from nektos/act
+	assert.NoError(t, err) //nolint:testifylint // pre-existing issue from nektos/act
 	defer readerArm64.Close()
 	_, err = io.ReadAll(readerArm64)
-	assert.Nil(t, err) //nolint:testifylint // pre-existing issue from nektos/act
+	assert.NoError(t, err) //nolint:testifylint // pre-existing issue from nektos/act
 
 	imageArm64Exists, err := ImageExistsLocally(ctx, "node:16-buster-slim", "linux/arm64")
-	assert.Nil(t, err)                      //nolint:testifylint // pre-existing issue from nektos/act
-	assert.Equal(t, true, imageArm64Exists) //nolint:testifylint // pre-existing issue from nektos/act
+	assert.NoError(t, err) //nolint:testifylint // pre-existing issue from nektos/act
+	assert.True(t, imageArm64Exists)
 }