"""Feed domain — 动态广场 (employee social feed).

Surfaces:

* ``/feed`` (employee) — public stream + my / department tabs, system
  birthday / anniversary cards, announcement sidebar.
* ``/admin/announcements`` (HR + IT) — author + schedule announcements.
* Scheduled jobs: daily celebration scan, celebrant/lead notifier,
  announcement pin-expiry.

All HTTP routes live in :mod:`app.domains.feed.router`. Business logic
lives in :mod:`app.domains.feed.service` and
:mod:`app.domains.feed.celebration_service`. ORM models are in
:mod:`app.domains.feed.models`.
"""