Bump Python packages to 0.9.0.dev2

[ciaranra]

Bumps all Python package versions from 0.9.0.dev1 to 0.9.0.dev2, following the RELEASING.md checklist:

• Version literals in the 11 pyproject.toml files (workspace root, quantum-pecos, pecos-rslib{,-llvm,-cuda,-exp}, and the five selene plugins), including the exact-version internal pins.
• Both lockfiles regenerated with the CI-pinned uv 0.11.14; diffs are version-lines-only.
• RELEASING.md historical note updated to reflect that the publish sequence was last exercised for 0.9.0.dev1 (confirmed on PyPI).

Verified: git grep 0.9.0.dev1 returns only the RELEASING.md historical note; uv lock --check passes for both lockfiles; just python-ci-sync-test succeeds and import pecos reports 0.9.0.dev2.