Detailed Description

Re-export shim for ``PromotedItem`` (Plan 142i [OP-5] relocation).

Purpose
-------
The promoted-item source model was relocated to
``oc_chat.registry.source.promoted_item`` so the ``source`` layer
(``canonical``/``hashing``) can resolve it for full three-projection hash parity
without ``source`` importing ``regenerate`` (a forbidden dependency direction).

This module is retained as a **load-bearing re-export shim** so pre-existing
importers outside Plan 142i's file scope keep working with zero edits
(``tools/seed_142_ingest.py``; ``oc_chat/registry/regenerate/pipeline.py``; the
render-refinements test). Do not add logic here — import ``PromotedItem`` from
its new home for new code.

Responsibilities
----------------
- Re-export ``PromotedItem`` from its new home so legacy import paths resolve.

Diagnostics
-----------
Domain: OC_CHAT.MAIN
Levels:
    L2 - module lifecycle
    L3 - (n/a — pure re-export)
    L4 - (n/a — pure re-export)

Contracts
---------
- Pure re-export: ``PromotedItem`` is defined in ``source.promoted_item``.

Dependencies
------------
- oc_diagnostics (structured debug logging via _dbg)
- oc_chat.registry.source.promoted_item (the relocated model)