🎨 Palette: [UX improvement] Enhance README accessibility and clarity

[Igor Holt (igor-holt)]

💡 What: This PR enhances the project's documentation UX by improving accessibility, status clarity, and system visualization.

🎯 Why: As an infrastructure project, the README serves as the primary interface. Improving its scannability and accessibility ensures a better onboarding experience and prevents misuse in production.

♿ Accessibility: Added descriptive alt-text to badges (e.g., 'License: MIT - Open source software license') to provide meaningful context for screen reader users.

📸 Before: Plain text description and basic badges.
📸 After: Structured documentation with a clear warning alert and a high-level architecture diagram.

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PR created automatically by Jules for task 10464951000305072557 started by Igor Holt (@igor-holt)

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[gemini-code-assist]

Code Review

This pull request enhances the project's documentation by adding an architecture diagram to the README, updating badges with descriptive alt-text, and including a caution notice for its experimental status. Additionally, it standardizes the visual identity for core orchestration components in the .Jules/palette.md file. Feedback was provided to improve the accessibility of the Mermaid diagram styles by explicitly defining a high-contrast text color for the highlighted nodes.

[gemini-code-assist]

To ensure the architecture diagram remains accessible and readable across different themes (such as GitHub's dark mode), it is recommended to explicitly set the text color for the highlighted node. The current background color (#f96) has poor contrast with white text, which is often the default in dark themes. Adding color:#000 ensures high contrast and better accessibility.

Suggested change

	style Arbiter fill:#f96,stroke-width:4px
	style Arbiter fill:#f96,stroke-width:4px,color:#000

[gemini-code-assist]

The standardized visual identity should include an explicit text color to guarantee accessibility. Since #f96 is a light color, specifying color:#000 ensures that the text remains legible regardless of the environment's default text color.

Suggested change

	**Action:** When representing the 'Arbiter Core' in Mermaid diagrams, use double-circle syntax `((Arbiter Core))` and apply a high-contrast style: `fill:#f96,stroke-width:4px`.
	**Action:** When representing the 'Arbiter Core' in Mermaid diagrams, use double-circle syntax `((Arbiter Core))` and apply a high-contrast style: `fill:#f96,stroke-width:4px,color:#000`.