"""Persistent backend package for the Change.org offline clone (stage R3).

The whole storage contract lives in ``db.py`` (self-contained module, no
relative imports, loadable via ``importlib`` from ``clone/app.py``):

* sqlite3 in WAL mode under ``CLAWBENCH_DATA_DIR`` (default: the
  site-local ``data/`` directory OUTSIDE the ``clone/`` candidate root),
* ordered ``schema_migrations`` (``0001`` initial schema -> ``0002``
  additive comments + optimistic row version),
* deterministic seed (captured petitions as ordinary rows, incl. one
  victory and one closed petition), persisted sessions, signatures with
  derived counts + goal ladder, comments, supporter updates.

Everything remains a local fixture: no production Change.org account,
mutation, network call, or real audience is ever involved.
"""