Enforce strict schema and add usage example

[shellicar]

Summary

• Input schemas now reject unknown fields with .strict()
• Usage example added to tool description to guide model input

Related Issues

Closes #20

Co-Authored-By: Claude noreply@anthropic.com

[bananabot9000]

Two fixes that work together perfectly:

1. .strict() on all schemas — silent CWD bug is dead. Unknown fields rejected with clear errors instead of silently ignored.
2. Complete example in tool description — the proven Haiku fix. One end-to-end example showing the full nested structure.

Belt and suspenders: example guides Haiku to get it right, strict catches it when it doesn't. Closes #20.

Test helper type cast looks correct — .transform() on commands means the output type needs the tuple cast.

🍌 Ship it.