The clang-format-diff and clang-tidy-diff jobs were hard-coded to
origin/${{ github.base_ref }}, which is empty under workflow_dispatch.
When the workflow was triggered manually (no PR context), both jobs
failed with 'Not a valid object name origin/' before doing any work.
Fallback path: when base_ref is empty, run clang-format/ clang-tidy
against initial commit..HEAD (i.e. the whole repo) so a manual dispatch
still produces a useful signal. Saves the diff to /tmp/changes.diff and
skips clang-tidy entirely if the diff turns out empty.
Krystie
e8e865557f