Replace the bespoke _pre_merge_git_repos loop and _merge_git_remotes
with a single _merge_git_repos_raw that does a name-keyed union merge
at the raw dict level: build parent_repos from _entry_to_raw, then
for each name in set(child) | set(parent) produce {**parent.get(n,{}),
**child.get(n,{})}. child.git after from_dict already has the full
merged set, so _merge_git_remotes is no longer needed.
didericis-claude
ff7a52c1d2