Add optional Typer, Rich, and telemetry learning scenarios

[codeforester]

Summary

Add optional chapters that show how consumers adopt Base-CLI integrations without making them required for the core demo.

Scope

• Provide a small Typer adapter example or variant.
• Show Rich output as an optional presentation layer.
• Show an optional OpenTelemetry lifecycle span with graceful degradation.
• Keep the default install small and fully offline.

Acceptance criteria

• Optional dependencies are isolated and documented.
• Missing integrations do not change the command exit status.
• Tests cover both the optional-enabled and minimal paths.

Non-goals

Do not duplicate every focused example already maintained in base-cli.