Fusionne dev dans feat/endpoint-alertes-predictives

Resout les conflits additifs entre les routes alerts, recommendations
et stats mergees sur dev (PR #79, PR #82) pendant le developpement de
cette branche : deps.py, router.py, openapi.py, openapi.json,
test_openapi.py et 20-backend.md conservent desormais les trois routes.

apps/backend/app/repositories/reading.py

@@ -0,0 +1,21 @@
+from collections.abc import Sequence
+
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models.energy import Reading
+
+
+class ReadingRepository:
+    def __init__(self, session: AsyncSession) -> None:
+        self._session = session
+
+    async def latest_by_site(self) -> Sequence[Reading]:
+        # `.distinct(site_id)` compile en `DISTINCT ON (site_id)` sous PostgreSQL : une seule
+        # ligne par site, la plus récente grâce à l'ordre composite qui suit.
+        requete = (
+            select(Reading)
+            .distinct(Reading.site_id)
+            .order_by(Reading.site_id, Reading.timestamp.desc())
+        )
+        return (await self._session.execute(requete)).scalars().all()

apps/backend/app/repositories/recommendation.py

@@ -0,0 +1,22 @@
+from collections.abc import Sequence
+
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models.energy import Recommendation
+
+
+class RecommendationRepository:
+    def __init__(self, session: AsyncSession) -> None:
+        self._session = session
+
+    async def list_all(self) -> Sequence[Recommendation]:
+        requete = select(Recommendation).order_by(Recommendation.recommendation_id)
+        return (await self._session.scalars(requete)).all()
+
+    async def get_by_id(self, recommendation_id: int) -> Recommendation | None:
+        requete = select(Recommendation).where(
+            Recommendation.recommendation_id == recommendation_id
+        )
+        recommendation: Recommendation | None = await self._session.scalar(requete)
+        return recommendation