Merge remote-tracking branch 'origin/v5.1-dev' into claude/native-registration-checks

v5.1-dev gained only the squash of #5533, whose tree equals #5533's last
head (8bf3aad), which this branch already contains, so the merge keeps
this branch's tree.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: QuantumExplorer