* chore: bump libfossil → v0.5.0

* chore: bump libfossil → v0.5.0 in leaf and bridge modules

The auto-generated bump-upstream PR only updated the root module's go.mod. The leaf and bridge modules pin libfossil independently and need the bump too — without this, the upcoming #112 cleanup (delete ridToUUID + simplify Agent.Diff using libfossil v0.5.0's UUIDFromRID + whole-checkin Diff) can't land on leaf since leaf's go.mod still resolves to v0.4.5.

Worth fixing the bump-upstream workflow separately to walk every go.mod under the repo, but treating that as a follow-up rather than blocking this PR on it.

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Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com> Co-authored-by: Dan Mestas <[email protected]> check-in: c52b0b3b44 user: [email protected] tags: trunk