Update installation docs for modern tooling

- Prioritize uv over pip throughout, with uv as the recommended installer
- Update repology badges: Debian 13, Ubuntu 24.04, Fedora 40/41
- Make Python 3.12 the default (3.11 still supported)
- Promote Homebrew as full-featured option for macOS and Linux
- Add dependency summary table aligned with maintainers.md
- Document uharfbuzz and fonts-noto requirements
- Remove outdated warnings and simplify 32-bit section