style: satisfy wsl_v5 blank-line-before-defer rule

Insert the blank line wsl_v5 requires above four defer statements
whose deferred closure does not share a variable with the immediately
preceding line, across internal/handlers, internal/httpfetcher, and
internal/imgcache. No behavior change.

internal/handlers/imageenc.go

@@ -66,6 +66,7 @@ func (s *Handlers) HandleImageEnc() http.HandlerFunc {
 
 			return
 		}
+
 		defer func() { _ = resp.Content.Close() }()
 
 		// Set response headers

internal/httpfetcher/httpfetcher.go

@@ -198,6 +198,7 @@ func (f *HTTPFetcher) Fetch(ctx context.Context, url string) (*FetchResult, erro
 
 	// If we fail before returning a result, release the slot
 	success := false
+
 	defer func() {
 		if !success {
 			<-sem

internal/httpfetcher/httpfetcher_internal_test.go

@@ -237,6 +237,7 @@ func TestMockFetcher_FetchesFile(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Fetch() error = %v", err)
 	}
+
 	defer func() { _ = result.Content.Close() }()
 
 	if result.ContentType != contentTypeJPEG {

internal/imgcache/service.go

@@ -315,6 +315,7 @@ func (s *Service) fetchAndProcess(
 
 		return nil, fmt.Errorf("upstream fetch failed: %w", err)
 	}
+
 	defer func() { _ = fetchResult.Content.Close() }()
 
 	// Read and validate the source content