fix(tools): reject empty TF frame names on GetROS2TransformTool

[Bartok9]

Summary

Validate target_frame and source_frame before TF lookup.

Testing

• Offline unit tests where ROS not required (uv pytest)
• AI-assisted; human-reviewed

Claim: bartok
Operator: bartok
Campaign: aerial-drone

[maciejmajek]

Hi @Bartok9, thank you for your ongoing contributions. Would you mind squashing the fixes (all your open fix PRs) into 2 or 3 separate PRs? That could help us move with the review faster.

[Bartok9]

Thanks @maciejmajek — totally fair, and sorry for the review surface area.

I'll consolidate the open small fix PRs into 2–3 themed PRs (rough cut):

1. ROS2 tools / timeouts / TF / topic-service-action name guards
2. agents / HRI / messages / communication guards
3. s2s + bench validation guards (or fold s2s into #2 if that stays cleaner)

Plan: squash-related commits on fresh branches from current main, open the replacements, then close the superseded one-fix PRs with pointers so nothing is lost. I'll start with the tools/ROS2 cluster first since those are the oldest.

Appreciate the patience and the clear guidance.

[maciejmajek]

Covered in #872, min_length=1 on target_frame and source_frame.