Stabilize guardian approval coverage

[aibrahim-oai]

Summary

• align the guardian permission test with the actual sandbox policy it widens and use a slightly larger Windows-only timeout budget
• expose the additional-permissions normalization helper to the guardian test module
• replace the guardian popup snapshot assertion with targeted string assertions

Why this fixes the flake

This group was carrying two separate sources of drift. The guardian core test widened derived sandbox policies without updating the source sandbox policy, and it used a Windows command/timeout combination that was too tight on slower runners. Separately, the TUI test was snapshotting the full popup even though unrelated feature text changes were the only thing moving. The new assertions keep coverage on the guardian entry itself while removing unrelated snapshot churn.