* fix(tasks): merge cross-lineage dependency content at branch cut
The dependency gate enforced timing but never content: a dependent's
fresh branch could miss a same-repo dependency's merged work when that
merge landed outside the branch's own ancestor chain (cross-cell edges
under one root, same-repo batch cross-root edges). After a successful
branch cut, each dependency's real merge target (resolve_parent_branch)
is fetched and, unless already an ancestor, merged into the new branch;
conflicts abort cleanly (branch stays at its cut point, warning + an
accumulating task marker note) and never fail the claim. Cross-repo
dependencies are skipped — no shared history. Zero git work for the
no-deps common case; resumes never re-enter (branch creation only).
* chore(foundation): regenerate lifecycle artifacts; reflow inherited prose
* [lineage] mypy-clean mock idioms in the lineage orchestration tests
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Co-authored-by: Renn F <rennf93@users.noreply.github.com>
