Release v7.131.0

Changed

• Release trains are the default way to ship: one train and one pull request per repository. Split only for a named major awaiting confirmation, an urgent security fix authorized in writing, or an accepted outsider issue, which ships promptly on its own release (#995)
• Review rounds review each branch whole once, then review glue only, using a review log of reviewed heads so certified items are not reviewed again (#995)
• Flaky tests never hang a release: CI gate guidance classifies a failure quickly, reruns a confirmed flake once and otherwise quarantines it with a tracked issue, never silently and never for security or critical-path coverage (#995)
• Agents decide what the repository or research can answer and ask the user only about human-only matters or undecided product choices (#995)
• Browser use closes only the pages and browsers an agent opened itself, one browser per lane (#995)