Read the project event stream

Engineering events for one project in delivery order: branch.changed (item changes on a branch or Base, one event per branch and actor within the page, with the touched entity ids and the origin diff-seq window they cover), branch.rebased (one event per branch per update-from-parent: the branch re-anchored onto new parent state, so re-read it — its already-delivered changes are never re-reported) and the branch review workflow (branch.created, branch.ready_for_review, branch.approved, branch.rejected, branch.merged, …, each naming the branch, its merge target and the people involved). Poll without a cursor to read from the beginning, or with start=now to receive an empty page whose next_cursor is the present (future events only, no history replayed); then store and pass back next_cursor: pages are bounded by the stream’s settled floor, so a stored cursor never skips an event that commits late. Delivery order follows next_cursor; occurred_at can be out of order across pages (historical imports carry past timestamps). Filter by comma-separated type and/or one branch (branch=<id> or branch=master for Base); a cursor minted under a filter admits that filter or a narrower one — widening is a 400 instead of a silent skip of the excluded events, so restart from an earlier cursor to widen. Events carry the project, branch ("master" means Base), actor and an app_url back into Flow.