ci: use strings.ReplaceAll (staticcheck QF1004)

strings.Replace(s, old, new, -1) is idiomatically strings.ReplaceAll.
golangci-lint's staticcheck flags it; this was the last remaining
blocker after enabling v2.11.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: jonnyzzz

internal/caddy/generator_test.go

@@ -208,6 +208,35 @@ func TestTemplateFunctions(t *testing.T) {
 	}
 }
 
+func TestWriteFileIfChanged(t *testing.T) {
+	tmpDir := t.TempDir()
+	path := filepath.Join(tmpDir, "Caddyfile")
+
+	changed, err := writeFileIfChanged(path, []byte("first"))
+	if err != nil {
+		t.Fatalf("writeFileIfChanged failed: %v", err)
+	}
+	if !changed {
+		t.Fatal("expected initial write to be reported as changed")
+	}
+
+	changed, err = writeFileIfChanged(path, []byte("first"))
+	if err != nil {
+		t.Fatalf("writeFileIfChanged failed: %v", err)
+	}
+	if changed {
+		t.Fatal("expected identical content to report unchanged")
+	}
+
+	changed, err = writeFileIfChanged(path, []byte("second"))
+	if err != nil {
+		t.Fatalf("writeFileIfChanged failed: %v", err)
+	}
+	if !changed {
+		t.Fatal("expected different content to report changed")
+	}
+}
+
 func TestGenerateContent_HealthCheckHTTP(t *testing.T) {
 	cfg := &config.Config{
 		Domain:    "example.com",
@@ -359,6 +388,6 @@ handle @{{.Subdomain}} {
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
 		// Template parsing and execution
-		_ = strings.Replace(tmplContent, "{{.Domain}}", data.Domain, -1)
+		_ = strings.ReplaceAll(tmplContent, "{{.Domain}}", data.Domain)
 	}
 }