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/services/render_dispatcher.py

@@ -1,96 +1,3 @@
-"""Render dispatcher — routes render jobs to Celery.
-
-All renders run via Celery workers (Flamenco removed in v2 refactor).
-"""
-import logging
-from datetime import datetime
-
-from sqlalchemy import select, update as sql_update
-from sqlalchemy.orm import Session, joinedload
-
-from app.models.order_line import OrderLine
-from app.models.product import Product
-from app.models.system_setting import SystemSetting
-
-logger = logging.getLogger(__name__)
-
-
-def _load_setting(session: Session, key: str, default: str = "") -> str:
-    """Load a single system setting (sync)."""
-    row = session.execute(
-        select(SystemSetting).where(SystemSetting.key == key)
-    ).scalar_one_or_none()
-    return row.value if row else default
-
-
-def dispatch_render(order_line_id: str) -> dict:
-    """Dispatch a render job to Celery.
-
-    Must be called from a sync context (Celery task or sync wrapper).
-    Returns {"backend": "celery", "job_ref": str}.
-    """
-    from app.config import settings as app_settings
-    from app.services.render_log import emit, clear
-
-    clear(order_line_id)
-    emit(order_line_id, "Dispatch started — loading order line data")
-
-    sync_url = app_settings.database_url.replace("+asyncpg", "")
-    from sqlalchemy import create_engine
-    engine_db = create_engine(sync_url)
-
-    with Session(engine_db) as session:
-        line = session.execute(
-            select(OrderLine)
-            .where(OrderLine.id == order_line_id)
-            .options(
-                joinedload(OrderLine.product).joinedload(Product.cad_file),
-                joinedload(OrderLine.output_type),
-            )
-        ).scalar_one_or_none()
-
-        if line is None:
-            emit(order_line_id, "Order line not found", "error")
-            logger.error(f"OrderLine {order_line_id} not found")
-            return {"backend": "none", "job_ref": "", "error": "not_found"}
-
-        product_name = line.product.name or line.product.pim_id or "unknown"
-        output_name = line.output_type.name if line.output_type else "default"
-        emit(order_line_id, f"Product: {product_name} | Output: {output_name}")
-
-        if line.product.cad_file_id is None:
-            emit(order_line_id, "Product has no CAD file — marking as failed", "error")
-            logger.warning(f"OrderLine {order_line_id}: product has no CAD file")
-            session.execute(
-                sql_update(OrderLine)
-                .where(OrderLine.id == line.id)
-                .values(render_status="failed")
-            )
-            session.commit()
-            return {"backend": "none", "job_ref": "", "error": "no_cad_file"}
-
-        cad_name = line.product.cad_file.original_name if line.product.cad_file else "?"
-        emit(order_line_id, f"CAD file: {cad_name}")
-        emit(order_line_id, "Dispatching to Celery render worker")
-
-        now = datetime.utcnow()
-        session.execute(
-            sql_update(OrderLine)
-            .where(OrderLine.id == line.id)
-            .values(
-                render_status="processing",
-                render_backend_used="celery",
-                render_started_at=now,
-            )
-        )
-        session.commit()
-
-    engine_db.dispose()
-    return _dispatch_celery(order_line_id)
-
-
-def _dispatch_celery(order_line_id: str) -> dict:
-    """Dispatch to the Celery render task."""
-    from app.tasks.step_tasks import render_order_line_task
-    result = render_order_line_task.delay(order_line_id)
-    return {"backend": "celery", "job_ref": result.id}
+# Compat shim — use app.domains.rendering.service instead
+from app.domains.rendering.service import dispatch_render
+__all__ = ["dispatch_render"]