Goal

Make the README install checks clearer for first-time users after creating an HTML export.

Acceptance

• Add one concise bullet in README Useful local checks near the browsertrace export notes.
• Mention that browsertrace export prints Wrote <path> after writing the HTML file.
• Keep this documentation-only; no runtime behavior changes.
• Update or add the focused metadata test that covers the new README note.

Verification

• uv run --python 3.11 --extra dev pytest -q tests/test_metadata.py -k export_success_output
• uv run --python 3.11 --extra dev pytest -q
• git diff --check