refactor(B1): migrate to domain-driven project structure

Move all models/schemas/services/routers into app/domains/.
Keep backward-compat shims in old locations for imports.
Preserves domains/rendering/tasks.py from Phase A.

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

backend/app/schemas/order_line.py

@@ -1,39 +1,3 @@
-import uuid
-from datetime import datetime
-from pydantic import BaseModel
-from app.schemas.product import ProductOut
-from app.schemas.output_type import OutputTypeOut
-
-
-class OrderLineCreate(BaseModel):
-    product_id: uuid.UUID
-    output_type_id: uuid.UUID | None = None
-    render_position_id: uuid.UUID | None = None
-    gewuenschte_bildnummer: str | None = None
-    notes: str | None = None
-
-
-class OrderLineOut(BaseModel):
-    id: uuid.UUID
-    order_id: uuid.UUID
-    product_id: uuid.UUID
-    product: ProductOut
-    output_type_id: uuid.UUID | None
-    output_type: OutputTypeOut | None
-    gewuenschte_bildnummer: str | None
-    item_status: str
-    render_status: str
-    result_path: str | None
-    thumbnail_url: str | None = None
-    ai_validation_status: str
-    ai_validation_result: dict | None
-    render_backend_used: str | None = None
-    flamenco_job_id: str | None = None
-    unit_price: float | None = None
-    render_position_id: uuid.UUID | None = None
-    render_position_name: str | None = None
-    notes: str | None
-    created_at: datetime
-    updated_at: datetime
-
-    model_config = {"from_attributes": True}
+# Compat shim — use app.domains.orders.schemas instead
+from app.domains.orders.schemas import OrderLineCreate, OrderLineOut
+__all__ = ["OrderLineCreate", "OrderLineOut"]