Context

The README PyPI install/useful local checks section currently has adjacent bullets that both explain when [ui] is needed:

- `[ui]` is needed for the local web UI, while SDK-only install is enough for trace capture integrations.
- SDK-only install can still use terminal commands like `browsertrace list`, `browsertrace show`, and `browsertrace export`; `[ui]` is only needed for the local web UI.

Both details are useful, but repeating the [ui] explanation in adjacent bullets makes the install checklist noisier.

Scope

• Merge those adjacent [ui] / SDK-only bullets into one concise bullet.
• Preserve both meanings: [ui] is needed for the local web UI, SDK-only install is enough for trace capture integrations, and SDK-only users can still run browsertrace list, browsertrace show, and browsertrace export.
• Leave install commands, PyPI links, release links, contribution links, templates, and unrelated bullets unchanged.
• Add or update a focused metadata test only if the existing README assertions need it.

Suggested verification

git diff --check -- README.md tests/test_metadata.py
uv run --python 3.11 --extra dev pytest tests/test_metadata.py -q

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