[codex] Fix Home summary notice dismissal

[r3dbars]

Summary

• tighten the Home local-summary notice dismissal path so the timer resolves the next notice state through the shared policy
• extend the focused Home summary notice test to prove the scheduled notice clears while an older timer leaves a newer notice visible

Repro signal

The June 8 self-sent Transcripted Feedback email showed meeting.local_meeting_summary_completed with chunk_count=1, while the green AI summary saved Home notice stayed on screen. That points at the Home notice lifecycle after completion, not the Gemma generation path itself.

Nearby follow-up

The same report also says Gemma setup can show ready while Home remains in Generating AI summary for a long time. I kept this PR scoped to the stuck saved notice; that slower generating state should be handled separately.

Verification

• bash run-tests.sh --filter HomeMeetingSummaryBetaPresentationPolicyTests
• bash build-deps.sh --force
• bash build.sh --no-open
• bash run-tests.sh