Bundles (lfx-arxiv, lfx-duckduckgo) change infrequently enough that a
nightly cadence is overkill. Drop the rename-to-`-nightly` and bundle
publish lanes from the nightly pipeline and add a dedicated
workflow_dispatch-only release_bundles.yml for purposeful releases.
- nightly_build.yml: drop update_bundle_versions.py invocation and the
src/bundles/*/pyproject.toml git-add guard.
- release_nightly.yml: remove build-nightly-bundles and
publish-nightly-bundles jobs; untether test-cross-platform and
publish-nightly-main from them.
- release_bundles.yml (new): build all src/bundles/* wheels, run a
cross-OS install smoke test, then publish to PyPI under their stable
names. Tolerates already-published versions so re-runs without a
version bump are no-ops.
release.yml still owns bundle publishing as part of main releases.
Manual follow-up (PyPI admin): delete the lfx-arxiv-nightly and
lfx-duckduckgo-nightly projects from PyPI.