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/product.py

@@ -1,72 +1,3 @@
-import uuid
-from datetime import datetime
-from pydantic import BaseModel
-from app.schemas.render_position import RenderPositionOut
-
-
-class ProductCreate(BaseModel):
-    pim_id: str
-    name: str | None = None
-    category_key: str | None = None
-    ebene1: str | None = None
-    ebene2: str | None = None
-    baureihe: str | None = None
-    produkt_baureihe: str | None = None
-    lagertyp: str | None = None
-    name_cad_modell: str | None = None
-    gewuenschte_bildnummer: str | None = None
-    medias_rendering: bool | None = None
-    components: list[dict] = []
-    cad_part_materials: list[dict] = []
-    notes: str | None = None
-    is_active: bool = True
-    source_excel: str | None = None
-
-
-class ProductPatch(BaseModel):
-    name: str | None = None
-    category_key: str | None = None
-    ebene1: str | None = None
-    ebene2: str | None = None
-    baureihe: str | None = None
-    produkt_baureihe: str | None = None
-    lagertyp: str | None = None
-    name_cad_modell: str | None = None
-    gewuenschte_bildnummer: str | None = None
-    medias_rendering: bool | None = None
-    components: list[dict] | None = None
-    cad_part_materials: list[dict] | None = None
-    notes: str | None = None
-    is_active: bool | None = None
-
-
-class ProductOut(BaseModel):
-    id: uuid.UUID
-    pim_id: str
-    name: str | None
-    category_key: str | None
-    ebene1: str | None
-    ebene2: str | None
-    baureihe: str | None
-    produkt_baureihe: str | None
-    lagertyp: str | None
-    name_cad_modell: str | None
-    gewuenschte_bildnummer: str | None
-    medias_rendering: bool | None
-    components: list[dict]
-    cad_part_materials: list[dict]
-    cad_file_id: uuid.UUID | None
-    thumbnail_url: str | None = None
-    render_image_url: str | None = None
-    processing_status: str | None = None
-    stl_cached: list[str] = []
-    cad_parsed_objects: list[str] | None = None
-    arbeitspaket: str | None = None
-    notes: str | None
-    is_active: bool
-    source_excel: str | None
-    render_positions: list[RenderPositionOut] = []
-    created_at: datetime
-    updated_at: datetime
-
-    model_config = {"from_attributes": True}
+# Compat shim — use app.domains.products.schemas instead
+from app.domains.products.schemas import ProductCreate, ProductPatch, ProductOut
+__all__ = ["ProductCreate", "ProductPatch", "ProductOut"]