Include inherited shared patches in patch validation #29

During a correctness pass with Astra we found the following issue:

Author's preface above. Issue details below written by Astra (AI assistant) on 2026-10-09.

rs <distro> check-patches only passes distros/<distro>/patch to the patch checker. The checker discovers files from that single directory, so inherited shared patches are missing from its checks.

The audit generated Jazzy recipes on osx-arm64. The ros2-swri-serial-util recipe references the shared patch, but this dry discovery check reported No recipes with patches found and exited successfully:

pixi run rs jazzy check-patches --dry --recipe ros2-swri-serial-util

This demonstrates the discovery gap, not that the patch itself fails to apply.

Code: tools/robostack.py and tools/check_patches_clean_apply.py.

Suggested change

Validate the effective merged patch set, including shared patches and distro overrides. Reuse Vinca's resolution rules where possible rather than maintaining another partial interpretation. Check the orphaned-patch command for the same directory assumption.

Acceptance criteria

• The shared ros2-swri-serial-util patch is discovered for Jazzy.
• Distro overrides replace the appropriate shared patch without testing an obsolete copy.
• Platform-specific patches retain the intended coverage.
• A non-applying shared patch makes the relevant check fail.