feat(intrants): add AchatIntrant + Fabrication SQLModel

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/models/__init__.py

@@ -10,3 +10,4 @@ from app.models.astuce import Astuce  # noqa
 from app.models.recolte import Recolte, Observation  # noqa
 from app.models.meteo import MeteoStation, MeteoOpenMeteo  # noqa
 from app.models.saint import SaintDuJour  # noqa
+from app.models.intrant import AchatIntrant, Fabrication  # noqa

backend/app/models/intrant.py

@@ -0,0 +1,57 @@
+# backend/app/models/intrant.py
+from datetime import datetime, timezone
+from typing import List, Optional
+from sqlalchemy import Column
+from sqlalchemy import JSON as SA_JSON
+from sqlmodel import Field, SQLModel
+
+
+class AchatIntrant(SQLModel, table=True):
+    __tablename__ = "achat_intrant"
+
+    id: Optional[int] = Field(default=None, primary_key=True)
+    categorie: str  # terreau | engrais | traitement | autre
+    nom: str
+    marque: Optional[str] = None
+    boutique_nom: Optional[str] = None
+    boutique_url: Optional[str] = None
+    prix: Optional[float] = None
+    poids: Optional[str] = None          # "20L", "1kg", "500ml"
+    date_achat: Optional[str] = None     # ISO date
+    dluo: Optional[str] = None           # ISO date
+    notes: Optional[str] = None
+    jardin_id: Optional[int] = Field(default=None, foreign_key="garden.id")
+    plantation_id: Optional[int] = Field(default=None, foreign_key="planting.id")
+    tache_id: Optional[int] = Field(default=None, foreign_key="task.id")
+    created_at: datetime = Field(default_factory=lambda: datetime.now(timezone.utc))
+
+
+class Ingredient(SQLModel):
+    """Modèle pour un ingrédient de fabrication (non persisté seul)."""
+    nom: str
+    quantite: str  # "1kg", "10L"
+
+
+class Fabrication(SQLModel, table=True):
+    __tablename__ = "fabrication"
+
+    id: Optional[int] = Field(default=None, primary_key=True)
+    type: str  # compost | decoction | purin | autre
+    nom: str
+    ingredients: Optional[List[dict]] = Field(
+        default=None,
+        sa_column=Column("ingredients", SA_JSON, nullable=True),
+    )
+    date_debut: Optional[str] = None      # ISO date
+    date_fin_prevue: Optional[str] = None # ISO date
+    statut: str = "en_cours"             # en_cours | pret | utilise | echec
+    quantite_produite: Optional[str] = None  # "8L", "50kg"
+    notes: Optional[str] = None
+    jardin_id: Optional[int] = Field(default=None, foreign_key="garden.id")
+    plantation_id: Optional[int] = Field(default=None, foreign_key="planting.id")
+    tache_id: Optional[int] = Field(default=None, foreign_key="task.id")
+    created_at: datetime = Field(default_factory=lambda: datetime.now(timezone.utc))
+
+
+class FabricationStatutUpdate(SQLModel):
+    statut: str