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/models/order_line.py

@@ -1,52 +1,3 @@
-import uuid
-import enum
-from datetime import datetime
-from decimal import Decimal
-from sqlalchemy import String, DateTime, Text, ForeignKey, Numeric
-from sqlalchemy.orm import Mapped, mapped_column, relationship
-from sqlalchemy.dialects.postgresql import UUID, JSONB
-from app.database import Base
-
-
-class OrderLine(Base):
-    __tablename__ = "order_lines"
-
-    id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
-    order_id: Mapped[uuid.UUID] = mapped_column(
-        UUID(as_uuid=True), ForeignKey("orders.id", ondelete="CASCADE"), nullable=False, index=True
-    )
-    product_id: Mapped[uuid.UUID] = mapped_column(
-        UUID(as_uuid=True), ForeignKey("products.id"), nullable=False, index=True
-    )
-    output_type_id: Mapped[uuid.UUID | None] = mapped_column(
-        UUID(as_uuid=True), ForeignKey("output_types.id"), nullable=True
-    )
-    gewuenschte_bildnummer: Mapped[str | None] = mapped_column(String(500), nullable=True)
-    item_status: Mapped[str] = mapped_column(String(20), nullable=False, default="pending")
-    render_status: Mapped[str] = mapped_column(String(20), nullable=False, default="pending")
-    result_path: Mapped[str | None] = mapped_column(String(1000), nullable=True)
-    render_log: Mapped[dict | None] = mapped_column(JSONB, nullable=True)
-    ai_validation_status: Mapped[str] = mapped_column(String(20), nullable=False, default="not_started")
-    ai_validation_result: Mapped[dict | None] = mapped_column(JSONB, nullable=True)
-    flamenco_job_id: Mapped[str | None] = mapped_column(String(100), nullable=True)
-    render_backend_used: Mapped[str | None] = mapped_column(String(20), nullable=True)
-    render_started_at: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
-    render_completed_at: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
-    unit_price: Mapped[Decimal | None] = mapped_column(Numeric(10, 2), nullable=True)
-    render_position_id: Mapped[uuid.UUID | None] = mapped_column(
-        UUID(as_uuid=True),
-        ForeignKey("product_render_positions.id", ondelete="SET NULL"),
-        nullable=True,
-    )
-    notes: Mapped[str | None] = mapped_column(Text, nullable=True)
-    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow, nullable=False)
-    updated_at: Mapped[datetime] = mapped_column(
-        DateTime, default=datetime.utcnow, onupdate=datetime.utcnow, nullable=False
-    )
-
-    order: Mapped["Order"] = relationship("Order", back_populates="lines")
-    product: Mapped["Product"] = relationship("Product", back_populates="order_lines")
-    output_type: Mapped["OutputType | None"] = relationship("OutputType", back_populates="order_lines")
-    render_position: Mapped["ProductRenderPosition | None"] = relationship(
-        "ProductRenderPosition", back_populates="order_lines"
-    )
+# Compat shim — use app.domains.orders.models instead
+from app.domains.orders.models import OrderLine
+__all__ = ["OrderLine"]