Initial commit: mini-erp (backend FastAPI + frontend React/Vite)

Base para el flujo de ramas por cliente.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

mini-backend/routers/purchases.py

@@ -0,0 +1,18 @@
+from fastapi import APIRouter
+
+from core.crud_router import make_crud_router
+
+router = APIRouter()
+
+_MARKETING_DOC_PATCH_HEADERS = {"B1S-ReplaceCollectionsOnPatch": "true"}
+
+for _resource in ("PurchaseOrders", "PurchaseDeliveryNotes", "PurchaseInvoices"):
+    router.include_router(
+        make_crud_router(
+            _resource,
+            tags=["Compras"],
+            key_field="DocEntry",
+            supports_orderby=True,
+            patch_headers=_MARKETING_DOC_PATCH_HEADERS,
+        )
+    )