Update install instructions to use pip

[ajtritt]

Summary

• Replace source-checkout install instructions with pip install from the published GitHub release tag.
• Remove uv from the prerequisites list.

Changes

• docs/index.md — Removed uv prerequisite. Replaced git clone / uv sync / source .venv/bin/activate with a single pip install command pointing to the 0.1.0 release zip.
• docs/quickstart.md — Same replacement in the Setup block.
• docs/cli.md — Removed the note about running uv sync and activating the virtual environment before using commands.
• docs/developer.md — Updated MCP troubleshooting to use which instead of uv run which, and pip install --force-reinstall instead of uv sync --reinstall.