refactor: replace DefaultLimitOffsetPage with LimitOffsetPage in multiple files and update timezone handling to use UTC

backend/app/db/pagination.py

@@ -3,19 +3,23 @@
 from __future__ import annotations
 
 from collections.abc import Awaitable, Callable, Sequence
-from typing import TYPE_CHECKING, Any, TypeVar, cast
+from typing import TYPE_CHECKING, Any, TypeVar
 
 from fastapi_pagination.ext.sqlalchemy import paginate as _paginate
 
 from app.schemas.pagination import DefaultLimitOffsetPage
 
 if TYPE_CHECKING:
+    from fastapi_pagination.limit_offset import LimitOffsetPage
     from sqlmodel.ext.asyncio.session import AsyncSession
     from sqlmodel.sql.expression import Select, SelectOfScalar
 
 T = TypeVar("T")
 
-Transformer = Callable[[Sequence[Any]], Sequence[Any] | Awaitable[Sequence[Any]]]
+Transformer = Callable[
+    [Sequence[Any]],
+    Sequence[Any] | Awaitable[Sequence[Any]],
+]
 
 
 async def paginate(
@@ -23,12 +27,7 @@ async def paginate(
     statement: Select[Any] | SelectOfScalar[Any],
     *,
     transformer: Transformer | None = None,
-) -> DefaultLimitOffsetPage[T]:
+) -> LimitOffsetPage[T]:
     """Execute a paginated query and cast to the project page type alias."""
-    # fastapi-pagination is not fully typed (it returns Any), but response_model
-    # validation ensures runtime correctness. Centralize casts here to keep strict
-    # mypy clean.
-    return cast(
-        DefaultLimitOffsetPage[T],
-        await _paginate(session, statement, transformer=transformer),
-    )
+    page = await _paginate(session, statement, transformer=transformer)
+    return DefaultLimitOffsetPage[T].model_validate(page)