Add Rich CLI and raw-Python tool guard decorator

[Sunny-commit]

Goal

Make OpenDecision useful and visually understandable from the terminal without requiring an agent framework.

Scope

• Add an optional Rich-powered CLI that loads a decision-pack YAML file and JSON state.
• Render decision, confidence, probability distribution, provider, and clear limitations.
• Add a framework-agnostic decorator for guarding Python tool calls.
• Preserve lazy Laya loading and a lightweight core install.

Acceptance criteria

• Copy-paste command documented in the README.
• Rich remains an optional dependency.
• Tests run without downloading model weights.
• Failure behavior and human-review paths are documented.
• Supported Python CI matrix passes.

Safety

Do not describe model confidence as a safety guarantee or generated explanations as Laya output.