docs: refresh README branding

[adohe]

What does this PR do?

• Replaces the old remote banner PNG with the repo-local AReno SVG logo.
• Adds an official documentation badge linking to https://asystem-ai.io/docs/areno/.
• Replaces the Compatibility matrix with a concise platform-support note.

Related issue

N/A

Type of change

• 🐛 Bug fix
• ✨ New feature
• 💥 Breaking change (public API / CLI behavior changes in a non-backward-compatible way)
• 📝 Documentation update
• ♻️ Refactoring
• ⚡ Performance improvement
• ✅ Test coverage improvement

How was it tested?

• Not run; README-only documentation update.

Checklist

• The PR title summarizes the contribution.
• Linked the related issue in the description (if any).
• Existing tests pass (pytest tests/ -k cpu).
• New behavior is covered by tests. (N/A for README-only documentation change.)
• Described the test commands run and any hardware limitations.
• Public API / CLI changes are additive and backward-compatible (see CONTRIBUTING.md).

Breaking change details

N/A

[gemini-code-assist]

Code Review

This pull request updates the README.md with a new documentation link, replaces the project logo, and simplifies the platform support description. It also adds the new SVG logo file. The review feedback suggests using an absolute raw GitHub URL for the logo in the README to ensure it renders correctly on external registries like PyPI, and replacing Chinese characters in the SVG attributes with standard ASCII/English names to avoid parsing and compatibility issues.

Important

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[xsuler]

/lgtm