feat(04-02): add OutputBlock reusable component

- Pre-formatted code block with label, copy button, and optional download button
- Copy button calls navigator.clipboard.writeText with 2s "Copied!" feedback
- Download button calls downloadFile(content, filename) when filename prop provided
- disabled prop gates both copy and download actions (SECU-01 security gate)

src/components/wizard/OutputBlock.tsx

@@ -0,0 +1,53 @@
+// src/components/wizard/OutputBlock.tsx
+// Reusable output block: pre-formatted content + copy button + optional download button.
+// disabled prop gates both actions (SECU-01 security acknowledgement gate).
+import { useState } from 'react';
+import { downloadFile } from '../../utils/downloadFile';
+
+export interface OutputBlockProps {
+  label: string;
+  content: string;
+  filename?: string;
+  disabled?: boolean;
+}
+
+export function OutputBlock({ label, content, filename, disabled = false }: OutputBlockProps) {
+  const [copied, setCopied] = useState(false);
+
+  async function handleCopy() {
+    await navigator.clipboard.writeText(content);
+    setCopied(true);
+    setTimeout(() => setCopied(false), 2000);
+  }
+
+  return (
+    <div className="mb-6">
+      <div className="flex items-center justify-between mb-1">
+        <span className="text-sm font-medium text-gray-700">{label}</span>
+        <div className="flex gap-2">
+          <button
+            type="button"
+            disabled={disabled}
+            onClick={handleCopy}
+            className="text-xs px-2 py-1 rounded border border-gray-300 disabled:opacity-40"
+          >
+            {copied ? 'Copied!' : 'Copy'}
+          </button>
+          {filename && (
+            <button
+              type="button"
+              disabled={disabled}
+              onClick={() => downloadFile(content, filename)}
+              className="text-xs px-2 py-1 rounded border border-gray-300 disabled:opacity-40"
+            >
+              Download
+            </button>
+          )}
+        </div>
+      </div>
+      <pre className="bg-gray-900 text-gray-100 rounded p-4 text-xs overflow-x-auto whitespace-pre-wrap">
+        <code>{content}</code>
+      </pre>
+    </div>
+  );
+}