Build an accessible OpenDecision Studio playground

[Sunny-commit]

Goal

Create a lightweight visual playground that explains OpenDecision within seconds.

Scope

• Isolated single-page studio.
• Paste or edit agent state and typed decision contracts.
• Visualize decision, confidence, probabilities, provider, and limitations.
• Clearly labeled sample mode when live Laya inference is unavailable.
• Document a future connection to the existing FastAPI endpoint.

Acceptance criteria

• Responsive layout and keyboard accessibility.
• Accessible contrast and reduced-motion support.
• Deterministic sample mode is never presented as live inference.
• Setup and build instructions are documented.
• UI tests or deterministic checks pass.
• No public deployment or analytics without explicit approval.